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ESPECIALLY FOR 



Rubber Manufacture 



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SAMUEL CABOT, Inc. 

Manufacturing Chemists 
BOSTON, MASS. .-. .-, U. S. A. 



COLORS 

and 

PIGMENTS 

for 

Rubber Compounding 



We are the Sole Proprietors and 
Originators of 

Basofor & Oximony 

The absolutely inert White Pigment with the 
special adaptability in Rubber Compounding. 
The Superfine Red Oxide with four times the 
coloring power of Antimony Sulphuret. Acid 
free and impalpably fine. 

E. M. & F. WALDO 

Executive Office: 11 Broadway 

New York City 

U. S. A. 



CRUDE RUBBER 



AND 



Compounding Ingredients 



A TEXT-BOOK OF 
RUBBER MANUFACTURE 



By HENRY C. PEARSON, F.R.G.S. 

Editor of The India Rubber World 

Author of "What I Saw in the Tropics," "Rubber Tires, 1 

"The Rubber Country of the Amazon," 

"Rubber Machinery," etc. 



THIRD EDITION 



NEW YORK: 

The India Rubber Publishing Company 

1920 






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Is 



Copyright, 1899, by Henry C. Pearson. 
Copyright, 1909, by Henry C. Pearson. 
Copyright, 1918, by Henry C. Pearson. 
Copyright, 1920, by Henry C. Pearson. 



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ID 



my 



©CI.A576234 







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for many years 
Principal of the Puncharo Free School 

Andover. Mass. 
who first awakened the author's inter- 
est in botany and chemistry 
this volume is affectionately dedicated 



PREFACE. 

Since the first edition of this book appeared, almost twenty 
years ago, the rubber business has grown notably. New sources 
of rubber have been developed in various parts of the world, and 
grades of rubber heretofore unknown have come into use. Plan- 
tation rubber, previously a negligible factor, has taken its place 
as a regular and dominating product. Progress in the reclaim- 
ing of waste rubber of all sorts has been constant and of great 
magnitude. The industry at large preserves the same general 
outline as formerly, with perhaps the single exception of the mak- 
ing of motor tires, today the greatest division in rubber manu- 
facture. Of new compounding ingredients there are many, of 
substitutes a great variety, and of processes, good and bad, thou- 
sands. In the revision of the book those of a real or a sug- 
gestive value have been utilized. The general plan of the book 
has not been altered. It remains a dictionary of compounding 
facts, an encyclopedia of rubber-factory practice. It is for rub- 
ber-factory use and bespeaks for itself the same favor that it 
found with the practical man when it first appeared. 

The superiority of such a collection over the most compre- 
hensive book of compounds doubtless will be apparent to the 
expert manufacturer, for this reason: When a manufacturer 
buys a set of compounds — and most of them are purchasable — 
he invariably acquires them not so much for use as for sugges- 
tion and comparison. The descriptions, therefore, of a great 
majority of the ingredients used in all lines of rubber com- 
pounding, and scores with which he may be unfamiliar, will be 
so suggestive to the practical man that new sets of compounds 
will be secured, each partaking of the individuality of the expert, 
and bearing the impress of the line of work done in the factory 
to which he is attached, and wholly free from the taint of imi- 
tation or counterfeiting, which is the bane of the purchased 
secret. It is felt that another point of superiority over the mere 
compound book will be found in the fact that no private formulas 
are given, those which are cited being typical rather than specific. 



4 PREFACE 

In the ten years that have elapsed since the second edition 
of this work appeared, great changes have taken place in rubber 
production and in processes of manufacture. The rise and domi- 
nance of cultivated rubber, the use of accelerators, the pressure 
cure, instead of the open dry heat, the progress in synthetic 
rubber production, are but a few of these. 

In the compilation and revision of this book free use has 
been made of English, German, and French standard technical 
works, as well as of technical journals, such as The India Rubber 
World, The India-Rubber and Gutta-Percha Trades lournal, Le 
Caoutchouc et la Gutta Percha, the Gummi-Zeitung, The lournal 
of the Society of Chemical Industry, and others. 

The author takes pleasure in acknowledging his indebted- 
ness for helpful suggestions to skilled manufacturers and super- 
intendents in both America and Europe, and to the following 
distinguished writers: P. G. W. Typke, F.C.S.; William Thomp- 
son, F.R.S.E. ; H. Grimshaw, F.C.S.; W. Lascelles-Scott, F.R. 
M.S., M.S.C.I.; Richard Gerner, M.E.; Dr. C. Purcell Taylor; 
Thomas Bolas, F.C.S., F.I.C. ; Professor D. E. Hughes, F.R.S. ; 
Granville H. Sharpe, F.C.S.; Carl Otto Weber, Ph.D.; Lothar 
E. Weber, Ph.D. ; A. Camille, the late Dr. Eugene F. A. Obach, 
F.I.C., F.C.S., M.E.E.E. ; Philip Schidrowitz, Ph.D. ; Dr. Joseph 
Torrey, Dr. David Spence, Professor Francis Ernest Lloyd, 
Hubert L. Terry, F.I.C; Cuthbert Christy, F.R.G.S., and many 
others. 

I have great pleasure also in gratefully acknowledging the 
assistance of members of my staff in the onerous work of proof- 
reading, indexing, etc. My thanks are also extended to Webster 
Norris, S.B., for his work in the revision of the technical and 
chemical portions of the volume. 



CONTENTS. 

Preface 3 

CHAPTER I. 

Crude Rubber, Chemical and Physical Characteristics. Sources of 
Supply. Grades : Para, Central, African, and East Indian 
Gums. Origin of Trade Names. Botanical Details. Plantation 
Rubber 7 

CHAPTER II. 

Some Little Known Rubbers and Bastard or Pseudo-Gums; Pos- 
sibility of Development of Their Use in the Factory 32 

CHAPTER III. 

Coagulation, Native Methods ; Chemical Systems, Mechanical Sys- 
tems, Coagulating Machines, Smoking, Oxydases 44 

CHAPTER IV. 

Vulcanizing Processes and Ingredients, Sulphur, Antimony Sul- 
phides, and Other Materials Used. Vulcanizing Pressures 
and Temperatures. Plantation Hevea and the Optimum Cure. 54 

CHAPTER V. 
Accelerators, Organic and Inorganic 80 

CHAPTER VI. 

Fillers and Ingredients Used in Rubber Compounds ; Sources, Prop- 
erties, and Uses of the Various Materials ; Unusual Ingredients 89 

CHAPTER VII. 
Substitutes for India Rubber, Natural and Artificial, 117 

CHAPTER VIII. 

Substitutes for Hard Rubber and Gutta-Percha, Including Cellu- 
lose Products 141 

CHAPTER IX. 

Resins, Balsams, Gums, Earth Waxes, and Gum-Like Substances 

Used in Rubber Compounding 153 

5 



CONTENTS 



CHAPTER X. 

Coloring Matters. Blacks, Blues, Greens, Reds, Browns, Whites, 

and Other Colors in Hard and Soft Rubber.. 176 

CHAPTER XL 
Acids, Alkalies, and Their Derivatives Used in Rubber Manufacture 194 

CHAPTER XII. 

Vegetable, Mineral, and Animal Oils Used in Rubber Compounds 

and Solutions , 213 

CHAPTER XIII. 

Solvents Used in Commercial and Proofing Cements ; Their Origin, 

Properties, and Methods of Use 228 

CHAPTER XIV. 

Miscellaneous Processes and Compounds for Use in the Rubber 
Factory : Waterproofing Compounds ; Shower-proofing ; Deo- 
dorization; Preserving Rubber Goods. Shrinkage of Rubber. 
Tire Fillers and Puncture Fluids 247 

CHAPTER XV. 
Synthetic Rubber 269 

CHAPTER XVI. 
Vulcanization Without Sulphur 275 

CHAPTER XVII. 
Reclaimed Rubber and Its Uses 290 

CHAPTER XVIII. 

Physical Tests and Analysis of Crude and Vulcanized Rubber. 

Specifications for Rubber Goods. Specific Gravity 302 

CHAPTER XIX. 

Primary Processes, Divisions in Rubber Manufacture, and Typical 

Compounds 351 

CHAPTER XX. 

Gutta-Percha : Its Sources, Properties, Manipulation, and Uses ; 
Components of Gutta-Percha ; Vulcanization ; Gutta-Percha in 
Compounds ; Methods of Analysis 376 

Index 399 



CHAPTER I. 

CRUDE RUBBER, CHEMICAL AND PHYSICAL CHAR- 
ACTERISTICS, SOURCES OF SUPPLY, 
ET CETERA. 

India Rubber is hard to define in scientific language. Its 
atomic structure is difficult to express, and means little when ex- 
pressed. It is a hydrocarbon, with the approximate formula 
QoH 16 ; but some oxygen is always present, which has led 
some to believe that oxygen is a necessary constituent. As a 
rule, however, the presence of oxygen is considered injurious, 
or a sign of deterioration. Rubber is as readily attacked by 
oxygen as is iron, and as surely destroyed by it. The formula 
C 10 H 16 is of too general a nature to be of value, since it covers 
rubbers of widely different physical properties, and even in- 
cludes gutta-percha. A more important chemical fact is that 
rubber is extremely resistant, being soluble only in carbon di- 
sulphide, carbon tetrachloride, turpentine, ether, gasoline and 
the like. 

The physical properties of rubber are softness, toughness, 
elasticity, impermeability, adhesion and electrical resistance. 
Its most characteristic, but not most important property, is 
that it can be repeatedly stretched to many times its length, 
returning each time to about its first dimensions. No other 
substance is at all comparable to rubber in this particular property, 
though one or more of the other properties are possessed in 
turn by many other substances. _J 

Rubber is derived chiefly from the milk or latex found in 
the bark of many trees, shrubs and vines, and to a certain extent 
also in the fruit, leaves, soft wood, or roots. The great families 
of the Euphorbiacece , in tropical America, and the Apocynacece, 
in tropical Africa, furnish most of the world's rubber. The 
Artocarpacece, of Central America and the East Indies, have a cer- 
tain importance, and the Composites, Asclepiadacece and perhaps 
other vegetable families contribute a certain amount. Altogether 
there are some thousands of species of trees, vines, bushes, 
weeds, roots, and tubers which contain rubber; but the Hevea, 
of Brazil, the Landolphia and Funtumia, of Africa, and the 



8 GRADES OF CRUDE RUBBER 

Castilloa, of Central America, together furnish practically the 
whole of the world's rubber. The tropics hold a vast store 
of wild rubber; but transportation, in these regions, is so 
difficult, and the growth of rubber trees under cultivation so 
rapid, that it is easier to grow rubber in accessible places than 
to get it out of the deeper forests; with the added advantage 
that plantation rubber is better prepared than would generally 
be possible in the forest. 

The latex, from which rubber is derived, is most often white, 
but is sometimes red or yellow. It is usually thick, like cream, 
though the solid matter contained may vary from 20 to 60 per 
cent. 

It has never been definitely settled whether the rubber 
exists as such in the latex, or whether it is developed by the 
process of coagulation. Some latex curdles immediately and 
spontaneously, like blood; others require the addition of 
chemicals or natural fermentation, like animal milk. In many 
cases the latex has never been made to coagulate. In some 
cases latex is used as a beverage, while in others it may be 
highly caustic or a deadly poison. 

Another substance developed out of the latex, along with 
the rubber, is commonly called resin. Some regard this as a 
broken-down, oxidized, perverted or "unripe" rubber. Other 
authorities maintain the existence of a series of resin-bearing 
tubes in the bark, independent of the system of milk tubes, but 
drawn out with the rubber milk by the same bark cuts. 

Rubber is composed of two substances or "principles," one 
of which, the adhesive principle, is easily soluble in ether, car- 
bon disulphide, and the like; while the other, the nervy or 
structural principle, is never really dissolved. The adhesive 
principle corresponds roughly to starch, while the nervy prin- 
ciple corresponds to cellulose. The adhesive principle seems 
to vary directly with the resin content, without being quite 
identical with it. There seems to be nothing else in nature 
which even approximates the insoluble or nervy part of rub- 
ber. It is this which gives rubber its elasticity, and enables 
it to take up compound; hence it forms the basis of rubber 
valuation. The adhesive principle, quite useful in cements and 



SOURCES OF RUBBER 9 

" frictions," forms the basis of a great number of " rubber-likes," 
and is of much less value. 

In the succeeding pages the leading kinds of rubber are 
described and classified according to commercial usage, while 
reference is made also to the geographical distribution of rubber. 

The Amazon valley, embracing hundreds of thousands of 
square miles of rubber-yielding forests in Brazil, Bolivia and 
Peru, is the center of the South American rubber industry, the 
whole product formerly being exported from the city of Para, 
whence the name " Para rubber." Several species of the Hevea 
produce this rubber, the best known being the Hevea Brasiliensis. 
Peru, Bolivia and Brazil also produce a rubber known as 
" caucho," and, in some markets, as " Peruvian rubber." This 
is the product of the Castilloa Ulei. Another species, Castilloa 
elastica, is the rubber tree of Nicaragua and other Central 
American states, which is also found in Ecuador, Venezuela, 
Colombia, and Mexico, and yields the rubber known as "Cen- 
trals." The Atlantic states of Brazil, south of Para, produce 
other rubber trees, from which come the grades known as 
"Mangabeira" and "Manigoba." 

"African " rubber is inferior to that obtained from South 
America, but through improved processes in gathering and 
curing, the various sorts are delivered in much better condi- 
tion year by year. African rubber is found on both the east 
and west coasts and throughout the great basins of the Congo 
and Niger rivers, in the Soudan region, and also on the island 
of Madagascar. The Landolphia, which include the Carpodinus 
and the Clitandras, are vines or creepers from which is pro- 
duced much African rubber. A considerable amount has been 
gained from such trees as the Ficus Vogelii and particularly the 
Funtumia elastica, which yields "Lagos" rubber. 

The East Indies today furnish but little wild rubber. The 
first rubber exported from that part of the world came from 
the Ficus elastica, from Assam, the name of which province has 
attached itself to rubber from other regions as well. The 
islands of Java, Sumatra, and Borneo, also Penang and other 
states in the Malay peninsula, and likewise French Indo-China, 
produce a certain amount of rubber, mostly from vines or 
creepers. 



10 GRADES OF CRUDE RUBBER 

Seaports, trading posts from which the first shipment is 
made, the name of a colony or country, or descriptive terms, 
as " thimbles," " buttons," " strips " — all or any of these may 
serve for names of different grades of crude rubber. A com- 
plete market report would indicate that there are a great num- 
ber of different qualities of rubber, many coming from the 
same source. This, however, is not wholly true. Take, for 
instance, the Para grades : Years ago any rubber coming from 
Brazil was called Para rubber. Later it was divided into 
" fine," " medium," and " coarse." Then the rubber from the 
islands in the lower Amazon became known as " Islands rub- 
ber," while that coming from further up stream was known 
as " Upriver," and these, too, were divided into fine, medium, 
and coarse. Now a dozen or more local names are applied to 
rubber from different localities, tributary to the Para market. 
At the same time, most of these rubbers sell at the same figures, 
grade for grade, with the exception of coarse. 

Something like this is true in the African rubber trade. 
For instance, a great number of local names are applied to 
the Congo rubber. The difference between " Equateur," " Kas- 
sai," and " Lopori " sorts may not be greater than between 
different lots from the same place. With a very few excep- 
tions, the names which follow are those used commonly in the 
leading markets of the world: 

PARA RUBBER. 

Rubber is classified at Para and Manaos into three grades, 
designated by the Portuguese words fina, entrefina, and sernamby. 
These grades in the United States are known as " fine," " me- 
dium," and " coarse," while in England they are classified 
as " fine," " entrefine," and " negroheads," the latter being di- 
vided to provide for a subgrade, " scrappy negroheads." The 
proportion of these grades exported through Para has been 
about 61 per cent, of fine, 11 per cent, of medium, and 28 per 
cent, of coarse. 

Fine Para rubber comes in large bottles or balls and, 
when cut, shows a surface closely marked with lines corres- 
ponding to the number of layers of rubber milk added during 
the smoking process. These layers are easily separated and, 



PARA RUBBER 11 

when stretched, are very transparent. This rubber smells not 
unlike smoked bacon. 

Medium or Entrefine resembles "fine," but is not so well 
cured, curds and globules of milk not perfectly coagulated being 
found between the layers. 

Coarse or Sernamby is made up of the residue, scraped 
from the collecting vessels, or from milk which has curdled 
before it could be smoked and made into " fine." This grade 
takes its name from the supposed resemblance of the scraps 
to the mussel fish called by the Portuguese sernamby. This 
rubber is known in England as " Negroheads" when in large 
chunks, more usual in the case of Upriver supplies. 

Besides this general classification of Para rubber, other 
names are in use, derived from the localities of origin. 

Islands rubber is that produced on the island of Mara jo, 
about 17,500 square miles in extent, and other islands in its 
vicinity in the delta of the Amazon, together with that from other 
parts of the state of Para, except the Xingu, Tocantins, and 
Tapajos rivers, which might well be called lower Amazon 
grades. The Islands " fine " and " medium " rubber is in the 
form of round or flat bottles, while the " coarse " or "sernamby " 
is in scraps massed into balls and round cakes, which give the 
name " negroheads " to this grade in the English market. 

Caviana rubber, named from the island that produces it, 
is the highest grade of Islands, and is today marketed as a 
distinct sort. It has a smooth, close grain, and is much in 
demand for fine work. 

Cameta rubber is so called from the port of that name, on 
the Tocantins river. It is noted for the superior quality of 
its " sernamby " grade, the " fine " being the same as from the 
islands, but rarely seen. This rubber comes in the form of little 
cups pressed into large " negroheads." 

Itaituba rubber comes from the port of that name, at the 
head of steam navigation on the Tapajos river, which enters 
the Amazon at Santarem. Rubber from this river is distin- 
guished for the rather gutty quality of the " fine " and " me- 
dium," and its stringy, dirty " sernamby." 

Xingu rubber, from the Xingu river, is noted for the spe- 
cially good cure of the " fine." 



12 GRADES OF CRUDE RUBBER 

Upriver rubber includes the product of the country border- 
ing the Amazon and its tributaries above Para, and that which 
conies from Peru and Bolivia through the large streams rising 
in those countries — such rivers are the Purus, Jurua, Javary, 
and Madeira. This rubber comes to market in biscuits and 
balls varying greatly in size and shape, a full average biscuit 
weighing about thirty pounds. The difference in price between 
Upriver and Islands rubber is due chiefly to the fact that the 
former, being derived from more remote localities, shrinks less 
after arriving in market. Upriver rubber is marketed also under 
such local names as " Manaos," " Madeira," " Bolivian," " Pu- 
rus," etc. 

Manaos rubber is named and exported from the city which 
is the capital of Amazonas, 1,200 miles up the Amazon river 
and the center of the rubber trade of the district. 

Madeira rubber, named from a great river which joins the 
Amazon below Manaos, is of excellent quality and produced in 
large quantities. It has a finer and closer grain than any other 
Upriver rubber except the Bolivian. 

Purus rubber comes down the river Purus, the largest of 
the rubber-yielding tributaries of the Amazon, and is probably 
the choicest of all the Para grades. A certain amount of the 
output of the Purus comes from a region formerly belonging 
to Bolivia, from which it was marketed as " Bolivian " rubber. 
That region has been acquired by Brazil and organized into 
the Federal territory of the Acre, which continues to produce 
a large amount of rubber. 

Bolivian rubber is floated down the Beni and other rivers 
in Bolivia to the Madeira, and thence to the Amazon. It for- 
merly met innumerable detentions from the cataracts in the 
upper Madeira, on account of which it became somewhat dried 
before reaching market. It has the advantage of being cured 
by a better class of labor than is common in Brazil, of having 
a tougher fiber and of being cleaner than most Upriver rubber, 
for which reasons it brings higher prices than any other. 

Not all the rubber of the Para grades now comes down 
the Amazon. A certain amount of the Bolivian output is shipped 
overland to the Pacific, and some by river to southern Atlantic 
ports. 



PARA RUBBER 13 

Peruvian rubber, in "ball" and "slab," was formerly applied, 
in the English trade particularly, to the class of rubber which 
will be described under the heading " caucho." In recent years 
however, Peru has supplied considerable rubber of the same 
character as Para — being derived from the Hevea. This rubber 
is exported from Iquitos down the Amazon, most of it going 
to Europe, where it is sold as Peruvian fine and negroheads 
(coarse), as well as ball and slab, and also "Peruvian weak." 
To a large extent Peruvian fine rubber loses its identity be- 
tween Iquitos and the consuming markets, and is classed merely 
as Para. 

Mollendo rubber comes from southern Bolivia, being trans- 
ported by steamers across Lake Titicaca and by rail to Mol- 
lendo, a Peruvian port on the Pacific, and thence principally 
to England. It is prepared in biscuits and sheets and is mar- 
keted at a price between Upriver and Islands. 

Angostura rubber comes down the Orinoco in Venezuela, 
from Cuidad Bolivar, which town formerly was known as An- 
gostura. It is of the same grades as the Para sorts. Some of 
the same class of rubber finds its way into Brazil, at Manaos, 
where its identity is lost. 

Orinoco rubber is the same as "Angostura." 

Matto Grosso rubber is from the state of that name in the 
southwest of Brazil, and reaches the market partly through 
tributaries of the Amazon and partly through the Parana, 
which discharges into the river La Plata. It comes in " fine," 
" medium," and " coarse," but principally the latter, little of it 
reaching the market at present. 

Caucho, which figures in all the markets of the Amazon 
region, and in statistics of Para rubber generally, is a distinct 
sort of rubber, inferior to Para, collected from the Castilloa Ulei. 
It is not cured by smoking but by admixture with the milk of 
lime, potash or soap. The physical characteristics of caucho, in 
the main, are the same as the Central American rubbers. The 
rubber of this sort exported by way of the Amazon formerly 
was obtained principally from Peru, but it has now been dis- 
covered throughout most of the rubber-producing regions of 
Brazil and Bolivia as well. Caucho figures very largely in the 



14 GRADES OF CRUDE RUBBER 

Para rubber trade. It comes to the market in three forms — 
" ball," " strip," and " sheet " (or slabs) — ranging in value in 
the order named. 

Caucho is the Spanish word for india rubber in general. 
When this particular sort of rubber first began to be marketed, 
it was obtained only in Spanish-speaking regions, and on com- 
ing down to Para, where the commercial language is Portu- 
guese, and being rubber of a distinct type, it not unnaturally 
became known commercially by the Spanish name, which really 
was a most convenient form of describing it, so as to avoid 
confusion in the trade. The commercial designation of rubber 
in Portuguese, in use at Para, is borracha. 

CENTRAL RUBBERS. 
Central American rubber, or " Centrals," includes that 
which is produced in all the states north of the Amazon valley, 
up to and including southern Mexico. It forms a distinctive 
class, being the product of a tree (the Castilloa elastica) not 
native elsewhere. In the United States the consumption of 
Centrals was once larger than that of Para rubber, but the 
yield has declined gradually to small proportions. This rubber 
is in good demand for certain uses, ranking in price below 
coarse Para. It has not the toughness or strength of fine Para, 
and possesses less elasticity. Centrals are classed usually as 
" sheet " and " scrap," besides which the terms "strip," " slab," 
" ball," and " sausage " are used. Greytown being a common 
shipping-point for Centrals, there is much confusion, one sort 
often getting substituted for another. Most of the yield of 
Costa Rica is exported through Nicaragua. The treatment of 
Centrals generally consists in mixing with the latex the juice 
of the " amole " vine, often in a hole in the ground, the product 
being " sheet " rubber. The rubber drippings which adhere to 
the bark of the tapped trees are peeled off when dry and called 
" scrap." The trade names below apply to the locality of origin, 
rather than distinctions in quality. 

Nicaragua rubber includes more than the product of that 
republic. The real Nicaragua rubber is drier, as a rule, than 
other grades of Centrals. Nicaragua sheet comes to market less 



CENTRAL RUBBERS 15 

clean than formerly, and the scrap brings a better price. Grey- 
town scrap is the best grade of Nicaragua rubber. 

Guatemala rubber is inferior and unequal in quality. The 
best is whitish in color, and the lower grades black with a tarry 
appearance. In curing, the rubber-gatherers pour the milk upon 
mats to dry, afterwards pulling off the product in sheets, press- 
ing them together for shipment. 

Guayaquil strip, from Ecuador, is imported in two grades 
— good and ordinary. Like the Guatemala rubber, the best 
has a whitish appearance. The inferior sort is porous and 
filled with a fetid black liquid, which carries an almost indelible 
stain. 

Esmeralda rubber, which also comes from Ecuador, is 
classed as " strip " and " sausage," the two grades coming to 
market in about equal quantities. 

Colombian is a pressed strip rubber, dark in color, some- 
times showing white when cut. It is graded " No. 1" and " No. 
2." Some of the rubber from Colombia bears local designations, 
besides varying in quality. These include : 

Cartagena, strip rubber, dark and tough, graded " No. 1" 
and " No. 2," selling at less than " Colombian." It comes also 
in thin sheets, rough or " chewed " in appearance, and tarry or 
sticky. The production has decreased very much of late. 

Virgin or Virgen rubber comes from Colombia in " sheet," 
" strip," and " slab." It is a product of a different tree (the 
Sapium tolimense) from the other " Centrals " described here. 

Panama rubber, like that from Nicaragua, embraces a wide 
range of / quality. The Pacific mail steamers bring together at 
Panama rubber from numerous ports, and confusion of grades 
is a result. What is marketed as " Panama " comes in " sheet " 
and "strip." 

Mexican rubber is of fair quality, but is received in con- 
stantly decreasing quantities. The grades, listed in the order of 
their selling value, are "ball" (or scrap), "strip," and "slab." 

Tuxpam strip comes from the Mexican port of that name. 
Very little of it is received, and that not of uniform quality. 

Honduras strip is of a quality similar to the Mexican, but 
is little produced. 



16 GRADES OF CRUDE RUBBER 

West Indian rubber has a good reputation for quality. It 
is not produced on the islands, but comes from Venezuela and 
Central America, and the designation is simply a general trade 
name used in England. 

It is to be kept in mind that the information given thus far 
under the general heading of " Central rubbers " relates to the 
native forest supplies from the countries mentioned. The prod- 
uct of the cultivated Castilloas is uniformly of a higher grade, 
is cleaner, and shows much less shrinkage. 

The grades which follow, though not entitled geographic- 
ally to be included as " Centrals," are in fact so classed, on 
account of their quality. 

Mangabeira rubber, from the Hancornia Speciosa, is so 
called from the local name of the tree producing it, in some of 
the Atlantic states of Brazil, south of Para. It is an alum-cured 
rubber and comes in sheets of a tawny red color, which resemble 
slices of liver. The thin sheet sells for more than the thick, as 
it is drier and better cured. Occasionally it comes in the form 
of balls. It is exported from Pernambuco, Bahia, and other 
points on the coast. 

Pernambuco is another name for Mangabeira- rubber, 
derived from the principal state and port from which it is 
shipped. 

Santos rubber, from another port, is also Mangabeira. 

Ceara. — Ceara rubber comes from a small tree particularly 
abundant in the Brazilian state of Ceara, known as the Manihot 
Glaziovii and the Manihot dichotoma. The milk exudes from the 
tree and coagulates in the form of " tears," which are gathered in 
scraps and balls. Of late years the rubber of the region referred 
to has received much attention and the output has been greatly 
increased. It has come to be known more generally by the local 
name of the tree, "Manicoba," of which there are now recog- 
nized to be several distinct species. One of these, the dichotoma, 
yields a superior quality of rubber, which is marketed as 
"Jequie" and "Remanso," these being locality names. It is 
also known as mule gum. 

Guayule is a Mexican rubber of a relatively new type which 
has come into use to a very large extent. This rubber is obtained 



AFRICAN RUBBERS 17 

from a shrub peculiar to the arid regions of northern Mexico 
and southern Texas — being practically the only rubber found in 
the United States. It differs from most rubber-producing plants 
in that it has no latex, the rubber being chiefly in the cells of the 
bark, a little in the wood, and none at all in the new shoots or 
leaves. The bark also contains balsam-like resins which are 
extracted with the rubber and are the cause of its softness and 
stickiness as compared with fine Para, for example. Generally 
the extraction of the rubber resolves itself into two processes: 
one purely mechanical and the other partly mechanical and partly 
chemical. Botanically the plant from which Guayule rubber is 
obtained is known as Parthenium argentatum. Guayule is also 
known as Pickeum gum. 

AFRICAN RUBBERS. 

African rubbers, as a class, are more adhesive and less 
elastic than Para rubbers, ranking with or below Para negro- 
heads. They often contain a liberal percentage of impurities, 
and for a long time their disagreeable odor and intractable 
nature hindered their introduction. But advancing prices for 
Para grades and fear of their coming scarcity led manufac- 
turers to experiment with African rubbers, until many uses 
were found for them. The result was a notable offset to the 
general upward tendency in price of the Para grades, although 
there are many purposes for which Africans never have been 
considered as competing with them. At the same time, the 
possibilities in the way of utilizing African sorts have not been 
exhausted, each year bringing out new uses. Besides, more in- 
telligent supervision of the work of preparing rubber in Africa 
has led to a great improvement in some grades, as compared 
with the condition in which formerly they came to market. 

The African rubbers are obtained from giant creepers, of 
which there is a score or more species on the continent and in 
the island of Madagascar, and also from several trees, the most 
important one of which, discovered first in the Gold Coast 
Colony, is known now to be widely distributed. There is now 
also a considerable production of "root rubber," obtained from 
underground creepers and marketed as " Lower Congo thim- 
bles," and also as " Benguela," according to the sources of pro- 



18 GRADES OF CRUDE RUBBER 

duction. The adulteration of African rubbers is not uncom- 
mon, being due to the dishonesty, not only of native gatherers, 
but doubtless also of some foreign traders on the coasts. But 
in most of the European colonies in Africa stringent regula- 
tions have been adopted to prevent such adulterations. On the 
Gold Coast the lumps of rubber brought to market by the 
natives were formerly cut into strips or buttons by machinery, 
before being exported. Latterly some of this work has been 
done in England, the rubber then being known as " Liverpool 
pressed." 

As a rule, African rubbers are obtained by the destruction 
of the trees or vines with the result that the total receipts from 
that continent are decreasing, despite higher prices than pre- 
vailed formerly. 

Ball is the classification of a large share of the African 
rubbers, which comes in every size from three or four inches 
in diameter down to half an inch or less. " Small ball " of the 
several kinds differs from the " large ball " in size, and is also 
dried and affords a smaller degree of shrinkage. 

Thimbles. — The natives, after gathering this rubber, cut 
it into cubes, about an inch square or less. Thimbles generally 
contain bark and sand, but very little moisture. 

Nuts. — Rubber thimbles from Ambriz are quoted some- 
times in European markets as "Ambriz nuts." 

Lump rubber comes in large pieces, varying in size and 
of irregular shapes. When packed in casks the pieces often 
become massed together in transit. It is from the best of the 
lump rubber that the most desirable buttons and strips are made. 

Flake comes in lumps, livers, and soft irregular masses, 
and is valuable in the factory chiefly for frictions and for soften- 
ing compounds. 

Paste is similar in quality but lower in grade than " flake." 
Accra flake and Niger paste are at the foot of the list, in respect 
to prices. The Niger is the cleaner material. 

Strips are lump rubber that is sliced and pressed by ma- 
chinery before it is offered to the trade. 



AFRICAN RUBBERS 19 

Buttons is a name applied to rubber similarly treated as 
in making strips, except that it is cut into small pieces, whereas 
strips have been marketed in every length up to ten feet. 

Biscuits is another name for " buttons." 

Oysters is another name for " buttons " or " biscuits." 

Tongues. — Some rubber formerly came to market in long, 
narrow, tongue-shaped pieces. The same grades are now more 
frequently seen in the shape of large balls. 

Niggers are of various sorts and from different sources. 
These rubbers are ball-like in some cases, having the appear- 
ance of masses of stringy rubber pressed together between the 
hands and wound into compact masses. 

Twist rubber is not unlike " niggers " in quality, but shows 
less shrinkage and differs in preparation and appearance. The 
string or strip-like pieces are wrapped about each other in order 
to give a twisted look to the balls. 

The list of rubber grades which follows is based upon a 
geographical arrangement, beginning with the upper west coast 
of Africa: 

FRENCH WEST AFRICA. 

This is an extensive region, extending from the Atlantic 
eastward to the precincts of the Nile, from which in recent 
years a great amount of rubber has come to French markets, 
the various grades being designated generally by local geographi- 
cal names. The leading grades now marketed from this region 
are: 

Conakry niggers. 

Soudan niggers and twists. 

Bassam niggers and lumps. 

Lahou niggers. 

Gambie "A," "A.M.," and " B." These last are of the 
" niggers " type. 

GAMBIA (BRITISH). 

Gambia niggers (No. 1, No. 2, No. 3) — These are classi- 
fied according to cleanliness, No. 1 and No. 2 being fairly clean, 
and No. 3 containing considerable soil. 

Bathurst. — Same as Gambia. 



20 GRADES OF CRUDE RUBBER 

SIERRA LEONE. 

Sierra Leone Twists (No. 1, No. 2, and rejections). — 
This is white and amber in color, of low shrinkage, and has 
bark and grit in it, but little moisture. 

Niggers (No. 1, No. 2, No. 3) are quite moist. No. 2 and 
No. 3 contain considerable soil. 

Cake. — Fairly clean, but wet. It is both red and white, 
the former bringing the better price. 

Manoh Twists. — This comes in the shape of tightly wound 
cords of rubber and works soft. In color it is black or white, 
the black being the better. 

LIBERIA. 

Liberian. — This is graded as Lump, Hard Flake, and Soft. 
It cuts yellow, is very wet, and is often a soft pasty rubber. 

assinee. 
What is known as Assinee is graded as follows: Assinee- 
Silky, Grand Bassam, Attoaboa, Lahou, Bayin, Half Jack. It is 
like Old Calabar, only it comes in chunks three inches square, 
is wet, and cuts yellow. These names are chiefly used in the 
English market. 

GOLD COAST COLONY. 

Gold Coast. — This is chiefly lump from which Strips and 
Buttons are made. There are also Biscuits and Niggers (hard 
and soft). The Flake is wet and has a bad smell, but other- 
wise is quite clean. 

Accra. — The Accra lump furnishes Strips and Buttons and 
is graded " prime," " seconds," and " thirds." The lower grades 
are Flake and Paste. 

Cape Coast. — This is another lump from which Strips and 
Buttons are manufactured and has for lower grades Flake and 
Soft. 

Salt Pond. — This Lump is also used in Strips and But- 
tons, the lowest grade being Flake. 

Addah Niggers (graded as No. 1 and No. 2) is very 
similar to Sierra Leone, but generally in smaller balls. It is 
not an Accra rubber, nor are Quittah Niggers or Axim. As a 



AFRICAN RUBBERS 21 

matter of fact, the grades from these different ports vary little 
if any, and are sold most frequently under the head of "Accra " 
rubber, from the name of the principal town in the colony. 

TOGOLAND. 

Lomi (or Lome) Ball. — The best grade of this is a clean, 
firm rubber and is fairly dry. The lower grades are rarely seen. 

NIGERIA (INCLUDING LAGOS). 

Lagos. — This lump is also turned into Buttons and Strips, 
while soft inferior lumps are sold as low grades without manu- 
facturing. It is very easily distinguishable from Accra by its 
odor. 

Niger. — The chief grade is Paste, which has an acid smell 
and is a low grade pasty rubber, wet but clean. 

Old Calabar. — It is graded as Blue, Lump, and Niggers, 
and is very bad smelling. The best lump is undoubtedly used 
for strips and buttons. 

Benin Ball. — Is generally dirty and has a rotten, woody 
smell. 

CAMEROONS. 

Cameroons. — The ball is graded as large, mixed, and small ; 
the clusters, which contain some fifty balls, as No. 1 and No. 2; 
and the knuckly ball, which is a small dry ball. This rubber has 
a fairly strong smell. 

Batanga Ball ("B," "E"). — Same as Cameroons, Ba- 
tanga being the name of a river and country in the Cameroons. 

FRENCH CONGO. 

French Congo Rubber is very similar to Cameroons, but 
the balls are larger. 

Gaboon is the best known flake and has for additional 
grades: lump, large "O" ball, and small "O" ball. The flake 
is free from dirt and is soft. 

Mayumba is both ball and flake. Another grade known as 
Mixed is a combination of the two and is sold as second quality. 

Loango. — Ball. 

These are names of rubber stations on the coast. The 
natives boil rubber milk, adding the juices of vines, and, while 



22 GRADES OF CRUDE RUBBER 

the rubber is hardening, wind it into balls, weighing from one- 
fifth pound to three pounds. The best rubber is not boiled, the 
milk drying on the wrists of the natives, as they tap the rubber 
vines. At the coast the balls are cut, to detect any cheating, 
and washed and packed in casks for export. 

BELGIAN CONGO (FORMERLY CONGO FREE STATE). 

Congo rubber comes in the shape of buttons, balls (No. 1 
and No. 2), red thimbles, and black thimbles. The ball is simi- 
lar to Cameroons, but tougher. The Dutch Congo ball is the 
same as the Congo ball, but is known as the best grade of that 
rubber. There is also the Congo (Kassai), black twist (graded 
as fine, mixed, and secondary), and red twist. The strips are 
among the toughest of African rubbers and are dry, with a 
woody smell. 

From the Lower Congo comes also the Luvituku, which is 
a red ball rubber, and from the Upper Congo, the following: 

Upper Congo. — Ball, red ball, twists, and strips, all of which 
are good tough rubber. 

Uele. — Strips, usually heated and fermented and bad smell- 
ing; cakes, wet, but clean. 

Sankuru. — Ball, very similar to Congo ball. 

Lake Leopold. — Graded as sausage and ball. It does not 
differ from the foregoing enough to warrant special description. 

Equateur. — In the form of balls (small and mixed). It is 
dark, dry, and clean, but contains some fermented rubber, which 
smells badly. 

Lopori. — Graded as ball (large and small), strips, and 
cakes. Some of the balls are fine and clean, while others contain 
fermented milk. Lopori also comes as sausage. 

Bangui. — Comes in the form of strips, firm and tough. 

Bussira. — Ball; a trifle softer than Lopori, but usually of 
excellent quality and dry. In use it develops a strong smell. 

Aruwimi. — Ball. This usually comes as large, firm balls. 
When opened much of the interior is found fermented. 

Mongalla. — In this the ball is similar to Upper Congo red 
ball. It also comes in strips, and is a good rubber. 



AFRICAN RUBBERS 23 

Some other designations of Upper Congo are Kassai, Ka- 
tanga, Ikelemba, Loango, Isanga, and so on. 

Bumba. — Ball; Buki. — Ball; Tava and Kwilu are all good 
Upper Congo grades that are not distinctive enough to dwell 
upon. 

Wamba. — This is a grade of thimbles and is a good black 
rubber, with only ordinary shrinkage. 

ANGOLA. 

Benguela. — Graded as sausage and niggers. Of the latter, 
No. 1 is clean and tough, and No. 2 contains a large percentage 
of red leaf. 

Mossamedes is practically the same, from a neighboring 
port. 

Loanda. — In this the grades, which are sausage and nig- 
gers, are similar to Benguela, but not so dry. There are also 
twists (red and black). 

Ambriz. — Chiefly thimbles or nuts; both are poor grades. 

EAST AFRICA. 

Uganda rubber comes from British East Africa. It is pre- 
pared in sheet form under modern methods, and arrives in good 
condition. 

Mozambique rubber is that coming from the port of Moz- 
ambique, from other ports in Portuguese East Africa, and per- 
haps from still other places in East Africa. It possesses some 
properties in common with the Madagascar rubbers. The rate 
of shrinkage is less than in most African sorts, and good prices 
are obtained. In the Liverpool market, which is the best for 
Mozambique grades, quotations are made for orange ball No. 1, 
ball No. 2, ball No. 3, liver, sausage, root, sticks or spindles, 
sticks removed, unripe. 

Orange Ball (resembling an orange in size and shape) is the 
choicest rubber. Other grades of Mozambique ball are distin- 
guished further as " white " and " red," the latter being inferior. 
Its reddish color is due to the fine bark mixed with it. The un- 
ripe contains more bark than rubber, and is not thoroughly cured. 

Sticks or spindles consist of spindle-shaped pieces made of 
slender strings of rubber wound around a bit of wood. Liver 
(or cakes) is in smooth pieces of irregular size. 



24 GRADES OF CRUDE RUBBER 

Lamu ball, liver, sausage, and root come from the Mozam- 
bique port of that name. They are not rubbers of a distinctive 
sort. 

MADAGASCAR. 

Madagascar rubber formerly ranked higher in price than 
most other African sorts, though today the highest price is 
obtained for some of the Congo sorts. Considering the greater 
loss sustained in washing, it costs nearly as much at times as 
fine Para. It is a favorite with manufacturers of hard rubber, 
on account of the fine lustrous polish which it assumes under 
the buffing wheel. The principal classification is between Pinky 
and Black. 

Pinky comes in round balls, weighing 1^2 to 4 pounds, black 
on the outside from exposure to the air, but having a pinkish- 
white look when cut. 

Black, also in small balls, when cut shows a dark color, and 
is more or less sandy and dirty. 

Tamatave being the principal seaport, its name is liable to 
be applied to any grades shipped from there. But what is 
described as "Prime Pinky Tamatave" is the best Madagascar 
rubber. 

Majunga rubber, from the West Coast town of that name, 
is a dark rubber of special excellence, ranking next to Pinky 
in price. 

Niggers (or negroheads) are designated as " East Coast " 
and " West Coast," and also as " red ball," and " gristly." They 
generally contain sand and dirt. 

Brown cure (or brown slab) is a still lower grade. 

Unripe is the lowest. This term is applied to balls contain- 
ing bark in the center. 

Rubber from Madagascar is sold at French auctions also 
as " Lombiro," the native name of a newly found plant, 
" Morondava," " Barabarja " (names of localities), and so on. 

Madagascar rubber is cured (1) by the use of salt water, 
in which case the water is never wholly expelled, leading to 
a heavy rate of shrinkage, and (2) by artificial heat. The island 
is rich in rubber forests, but the exports are restricted by the 



EAST INDIAN RUBBER 25 

wasteful methods of the natives, which exhaust the trees and 
vines, particularly near the coast. 

EAST INDIAN RUBBER. 

Assam rubber, the product of the Ficus elastica, is strong 
and of firm texture. It is fairly elastic, though often less so 
on account of carelessness in gathering and the introduction 
of impurities. There are four grades usually (No. 1 to No. 4), 
of which the lower ones are extremely dirty and contain soft 
rubber. The better grades when cut have a glossy, marbleized 
appearance, somewhat pinkish in color. Assam rubber is mar- 
keted in small balls, made by winding up strings of rubber 
dried on the trees, and also in oblong slabs of irregular size, 
wrapped in plaited straw. The output has declined for sev- 
eral years. Meanwhile the same species has been found in 
Burma, where the production of rubber has increased, though 
the whole output of forest rubber from British India is now 
smaller than at an earlier period. 

Rangoon rubber is the product of Burma, exported through 
the port of Rangoon, and differs so little from Assam rubber 
as to require no separate description. Four grades are mar- 
keted, at practically the same prices as for Assam rubber. 

Java rubber, from the island of this name, is dark and 
glossy, of a deeper tint than the Assam sorts, with occasional 
red streaks. Otherwise, its history and characteristics are nearly 
identical with those of Assam rubber. Three grades are recog- 
nized. The milk dries on the surface of the trees, on exposure 
to the air, and the shrinkage of the better grades is slight. 

Jelutong. — See Pontianak. 

Penang rubber (from one of the states in the Malay 
peninsula, including the island of Penang) is also very similar 
to that from Assam. There are three or four grades, at slightly 
lower prices than the Assam sorts bring. 

Borneo rubber ranks below the other Asiatic sorts, being 
lower in price, with a higher rate of shrinkage. It is of a 
whitish color, changing with age to a dull pink or red. It comes 
to market shaped like pieces of liver, and is soft, porous, or 
spongy. The pores are filled with salt water or whey, for the 



26 GRADES OF CRUDE RUBBER 

reason that salt is used to coagulate the rubber, and the water 
evaporating leaves a saline incrustation in the cells. There are 
three grades, the first of which is a good rubber, while the 
lowest, when cut, is almost as soft as putty, and is worth little. 

Pontianak, also known as jelutong, gutta jelutong, Gam- 
bria, besk and fluvia, is a low-grade rubber, chiefly from Borneo. 
It is the product of the latex of the Dyera costulata, and as 
gathered by the natives is doped with kerosene and earthy mat- 
ters, still further lowering its value. The gum was formerly 
classed with low grade guttas, as it was often used by the 
Chinese to adulterate the high-grade guttas. It is, however, not 
a gutta but a very resinous rubber. The rubber content is about 
10 per cent, and when crude rubber was high it was extracted 
at a profit and hundreds of tons of it used. 

There are several grades, as Palembang, Pontianak, Sara- 
wak, Bandjermassin, etc., the names being taken from the dis- 
tricts in which the gums are gathered. 

Pressed or Refined Pontianak in its naming indicates 
sufficiently its characteristics. It contains less of the usual im- 
purities, has no odor of kerosene, and on washing and drying 
loses from 40 to 50 per cent. It brings 6 or 7 cents a pound more 
than the ordinary grades. 

Gutta-Percha. — See Chapter XX. The highest grades, 
of which there are several, are well typified in what is known 
as red Macassar, which brings $2.00 a pound, as compared 
with the low grades at 19 and 24 cents. The following are 
low-grade guttas: 

Gutta-Siak (also called book gutta). — This is a low- 
grade gutta sometimes mixed with jelutong. It is prepared at 
Siak in Sumatra and its port of shipment is Singapore. Its 
regular form is a square folded sheet, or "book" with rounded 
edges, made by laying a sheet of the softened material in a series 
of folds, meeting in the center. The final end folds, at right 
angles to the first, producing the round-edge square book. 

Cold gutta-siak cuts tough, gummy and wet and may be 
cracked or split off by a light blow. The fracture shows a closely 
laminated mixture of pinkish gutta and white jelutong, giving a 
fibrous appearance. The fracture is interspersed with specks of 



PLANTATION RUBBER 27 

reddish bark. The odor of gutta-siak is slightly earthy. The 
usual impurities include moisture, bark and clayey earth. The 
loss on cleaning and drying is about 20 to 25 per cent. The 
clean gutta is firm and tough with some elasticity and is dark in 
color with a slightly reddish hue. Siak is like Souni. 

Gutta-Cotie, exported from Singapore. This is a low- 
grade gutta of somewhat higher grade than gutta-siak because it 
does not contain an admixture of jelutong. It is prepared in 
sheets, rolled three inches in diameter, cut into approximately 
one-foot lengths. It is somewhat less barky than gutta-siak. The 
shrinkage is about 15 per cent. Normally the market price of 
gutta-cotie is about 30 per cent, higher than that of gutta-siak. 

Gutta-Penang. — In the ascending scale, gutta-penang (ex- 
ported from Singapore), stands next above gutta-cotie in qual- 
ity. It is prepared in rolled sheets, five or six inches in diameter. 
The rolls are cut lengthwise and crosswise into pieces about six 
or eight inches long to expose the interior for inspection. The 
color is strongly pinkish, slightly specked with bark. The qual- 
ity and price are practically that of gutta-cotie. 

Souni is made up of Gutta Derrian, Dichopsis oblongata, 2 ; 
Gutta Sundeck, Payena Lerii, 3; Gutta Pouteh, Bonha-balen, 1. 

OCEANICA 
New Caledonia rubber comes in cakes weighing from 
13 to 22 pounds. It is brown to black in color; very pure, 
slightly smoky. The amount of shrinkage is 18 to 20 per cent. 

PLANTATION RUBBER. 
In the first edition of this work two lines seemed enough to 
devote to plantation rubber, since so little had then appeared 
in the market. In fact, with the exception of a few scientists 
and a smaller number of enthusiastic' planters, no one at that 
time seemed to regard rubber cultivation as a practical propo- 
sition, and the rubber manufacturers were not the least preju- 
diced against undertakings in this line. Now, however, 81 per 
cent, of the world's supply of rubber is derived from plan- 
tations. Since 1900 the world's annual production of crude 
rubber from all sources has increased from 54,000 tons to 270,- 
000 tons. The leading factor underlying this rapid growth is 



28 GRADES OF CRUDE RUBBER 

the extensive use of rubber for motor-vehicle tires. The extra 
rubber came almost wholly from plantations. 

Production of Plantation Para rubber is also established 
on a scientific basis. Every phase of its cultivation and pro- 
duction proceeds under the close study and carefully planned 
experiments of government and plantation association experts. 
The measures have practically attained the economical produc- 
tion of standard Para grades capable of supplanting the best 
wild Para for essentially every purpose. 

The prediction was made in 1909, by the planting interests 
of the Far East, that when the Hevea trees then planted should 
reach tappable size, Ceylon and Malaya would alone produce as 
much rubber as at that date entered into the world's total con- 
sumption. This result was attained in 1914. The growth by 
years is interesting. 

Year Pounds Year Pounds Year Pounds 

1903 47,040 1908 4,032,000 1913 106,664,320 

1904 96,320 1909 8,064,000 1914 159,891,200 

1905 324,800 1910 18,368,000 1915 241,622,080 

1906 1,142,400 1911 32,298,560 1916 341,936,000 

1907 2,240,000 1912 63,881,320 1917 (est). 492,800,000 

Any fear of overproduction of rubber, through the coming 
into bearing of so many planted trees, is offset by the fact that 
thus far the sources of wild or forest rubber, with the sole ex- 
ception of the native Hevea (Para) trees in Brazil, are being 
exhausted by the extraction of their product. Where trees and 
vines are killed by the rubber gatherers, there may be an in- 
creased yield from a given country for a while, due to the work- 
ing of new areas from time to time, but ultimately the principal 
forests are overrun, after which the output falls off. 

The cleanliness of plantation as compared with forest rub- 
ber has been an attraction from the beginning, and the higher 
price paid for the former has been due to its greater content, 
bulk for bulk, of rubber. Originally it proved deficient in 
strength as compared with the Brazilian product. For some pur- 
poses the deficiency of nerve of the new rubber did not prove 
a disadvantage, as, for instance, in solution making, in which it 
has been largely used. Gradually, however, it has replaced Para 
in practically every use to which the wild gum is put. 



PLANTATION RUBBER 29 

Rubber from Hevea plantations was at first clearly not 
identical with the product of the same species under forest con- 
ditions. The question was discussed as to whether this differ- 
ence was due to the plantation rubber not being smoked, as is 
done with Brazilian rubber. A reason now more generally given 
is that, owing to the tapping of planted trees having been begun 
at a very early age, the product was " immature." At least plan- 
tation rubber can now be had with more strength than formerly, 
which may be due either to increased age of the trees or to 
better methods of collection, coagulation, and care in subsequent 
storage and shipment. 

Plantation or Plantation Para is the term applied in 
the trade to the new class of rubber. " Ceylon," " Malaya," 
" Straits," "Java," and " Sumatra" are also applied, but these are 
merely local designations, indicating no difference in quality, all 
being produced by cultivated Hevea. What is more important 
is the growing practice of planters of stamping their product 
witlr trade-marks, by means of which buyers may know abso- 
lutely the source of any particular purchase, which is helpful 
when a producer of several tons in a year is attempting to estab- 
lish a reputation for quality. Plantation Para is produced in 
various forms, as follows: 

Biscuits. — Prepared by allowing the rubber milk to set in 
shallow receptacles, with or without acetic acid, and washing and 
rolling the cake of rubber which appears at the top more or less 
circular in form — usually 1/16 to 1/8 inch in thickness and 10 
to 14 inches in diameter. 

Sheets. — Formed in the same way as biscuits, but rectangu- 
lar in outline. On account of their shape they lend themselves 
to more economic packing. Biscuits and sheets are sometimes 
pressed together to form blocks. 

Crepe. — This rubber, on account of the washing and tearing 
which it undergoes between the rollers of the washing machine 
used in its preparation, contains a minimum of impurities. It has 
an irregular surface, is uneven in thickness, and, like lace or 
flake rubber, dries rapidly. On account of the washing which 
some manufacturers subject all rubber to, it has been questioned 
whether the extra labor involved in its preparation will be paid 



30 GRADES OF CRUDE RUBBER 

for by the extra price realized. Prepared in lengths of 3 to 6 
feet, and widths of 5 to 12 inches, and graded according to color. 

Worm. — The product obtained by cutting irregular sheets 
of freshly coagulated rubber into thin worm-like rods, shears 
or machinery being used. By passing the dry worms through 
ordinary washing rollers they are bound together into an even 
strip of crepe. 

Lace. — Very thin perforated sheets of considerable lengths. 
It comes from the machine in a continuous strip, and is cut 
into pieces 6 feet long as it runs on to wire trays. It is some- 
times pressed later into biscuits or sheets. 

Flake. — Obtained by placing small pieces of freshly coagu- 
lated rubber in a small rolling machine or washer, the corru- 
gations of which run horizontally; the rollers are close to- 
gether and the cut rubber issues as thin strips. 

Block. — Made from pressing together sheets, biscuits, or 
other forms of rubber, in a freshly coagulated or partly dry 
state, in sizes usually 10 x 10 x 6 inches, the chief purpose being 
to reduce to a minimum the surface exposed to the air after 
preparation. 

Scrap. — The remnants obtained after tapping, rolled into 
balls or made up into cakes. It is shipped with or without other 
preparation; it is sometimes made into crepe. It brings a com- 
paratively high price. 

Of these various forms the present accepted types with their 
market names are : 

First Latex Crepe. — A thin, pale, and clean creped sheet, 
the best grade of Plantation Para. 

Amber Crepe. — This comes in four grades, described as 
" gristly blanket." It is rough, thick, and light-colored. The 
other grades are similar in form but vary in color to dark amber, 
frequently mottled in appearance. 

Brown Crepe. — A lower grade than amber crepe, varying 
from thick to thin sheet ; light to dark-brown color. Frequently 
it is specky with barky impurities, requires washing, and is 
easily torn apart in the sheet. 



PLANTATION RUBBER 31 

Smoked Sheet, Ribbed Standard Quality. — This form 
has the distinctive smoked Para odor, varies in color from 
light to dark-brown, and viewed by transmitted light, is trans- 
lucent. It strongly resists stretching and may be distended into 
a thin film exhibiting marked tensile strength and stretch. 
The surfaces are embossed with various designs of ribbing, 
sometimes including plantation names. These designs serve as 
trade-marks for the identification of the produce from individual 
plantations. 

Smoked Sheet,, Plain Standard Quality. — This is the 
same in all respects as the "ribbed standard quality" except 
that it has no ribbing. 

Unsmoked Sheet, Standard Quality. — The same as 
plain smoked sheet except unsmoked. 

Colombo Scrap. — Massed clear, light-brown strings and 
bits of high-grade rubber, more or less specked with bark. 

Ceara plantation, from Manihots, comes from Ceylon and 
Malaya, and from some German colonies in Africa. 

Mexican plantation is very clean, not differing otherwise 
in quality from the product of the same tree {Castilloa) under 
forest conditions. It comes as strips, when the latex is creamed, 
coagulated, and run between rolls, and as Grena when the pro- 
duct is scrap-picked from the cuts on the trees and coagulated 
only by exposure to the air. 

Trinidad plantation, Tobago plantation, West Indies plan- 
tation, Central American plantation, Guayaquil "Castilloa," 
and such terms relate to the product of cultivated Castilloa trees 
in the regions indicated. A certain amount of Castilloa planta- 
tion rubber also comes from Ceylon and Java. 

Congo plantation, from various species, comes from Belgian 
Congo (Congo Free State). 

Uganda plantation comes from British East Africa. 

Rambong is the native name in the Far East for the Ficus 
elastica, which produces the Assam rubber of commerce. A con- 
siderable amount of cultivated Java and Ceylon Ficus rubber is 
sold under this name. This comes in crepe, sheet, and block. 



CHAPTER II. 

SOME LITTLE KNOWN RUBBERS AND BASTARD 
OR PSEUDO GUMS. 

From time to time reports come in from all over the tropi- 
cal world regarding the discovery of gums, some of which are 
similar to india rubber, while others are more like gutta-percha. 
In a few instances these gums have appeared on the market, 
in due time, under various names and have been useful. This 
is not the rule, however, and it is due to a variety of reasons. 
The first is the scientific attitude of those who primarily ex- 
amine the samples received at the great centers of civilization. 
Unless gums are of high grade, and bear promise of being 
nearly as valuable as a good grade of india rubber or gutta- 
percha, they are usually pronounced worthless, or nearly so. 
Nevertheless, rubber manufacturers are ever in the market 
for these products, and would welcome many of the pseudo 
gums and find large uses for them, if once they were within 
reach. 

Aside from the scientific attitude is the indifference of the 
gatherers in their native wilds, of the importers who see little 
profit in such cheap gums, and of the manufacturers them- 
selves, who wait until a neighbor has tried something new be- 
fore venturing to experiment. 

One has only to recall what is needed in rubber com- 
pounding to see how valuable many of these gums could be 
made. For example, sometimes simple stickiness is called for, 
in another case only insulating qualities and stickiness, in still 
another, water-proofing qualities and stickiness, and, it is well 
to add here, where only one valuable quality exists in a gum 
others can often be supplied. As a matter of fact, in the 
present state of compounding and manipulation, the presence 
of resins is not heeded, short life can be overcome, and intracta- 
bility can be done away with. 

32 



ABBA RUBBER— ALMEIDIN A 33 

It is with the hope that some of the gums mentioned in 
the following pages may be useful in rubber manufacture that 
space has been given to them. 

Abba Rubber. — This is from Lagos, probably the product 
of the Ficus Vogelii. It is low grade, cures soft and short, 
and contains a large percentage of resin. The trees are most 
abundant in Grand Bassam, and grow rapidly to great size, 
single trees often yielding 10 or 12 pounds in a season. The 
milk is coagulated by adding vegetable acids and boiling. The 
rubber is bright red. It contains about 55 per cent, rubber and 
45 per cent, resin, and forms 30 per cent, of the latex. The 
washing loss is 10 to 14 per cent. One report is that the latex 
of this tree is mixed with that of Funtumia elastica, the mixture 
being called by the natives " aba-odo." 

Abyssinian Gutta. — An adhesive acid gum of an earthy 
brown color, similar to common gutta in external appearance. 
Softens in water, but keeps a very great elasticity. On drying 
it remains exceedingly adhesive, therefore could not be used in 
place of gutta-percha, but with proper treatment would un- 
doubtedly make an excellent friction gum. 

Almeidina. — This comes from West Africa, particularly 
from the Cameroons and Angola, and has been found in the 
Solomon Islands. Its source is a shrub with succulent stems, 
all of which are tapped. The milk is boiled and the resultant 
balls dried in the sun. It comes to market in small and sul- 
phur-colored nodules, resembling potatoes, for which reason 
it sometimes has been called " potato gum." When broken 
open, these balls look like putty, and although quite brittle 
when cold, the gum easily softens in warm water and may be 
drawn out in threads, which are possessed of some elasticity. 
It is completely melted at 240 degrees F., and remains rather 
sticky after melting. It almost completely dissolves in cold 
benzine; in fact, nearly all of the solvents ordinarily used in 
rubber manufacture dissolve it. It mixes and dissolves with 
rubber in almost any proportion and up to 25 per cent, at 
least. Not only does it not injure the rubber, but is said to 
be beneficial to it. In working on the mill a pungent vapor 
arises from the mass, which, however, has no poisonous effect. 



34. LITTLE KNOWN RUBBERS 

In using this gum, a little caustic soda sometimes is added to 
the water when it is being washed; some manufacturers add 
tannic acid. Animal or vegetable fixed oils do not dissolve 
Almeidina, and therefore when mixed with it are apt to rot it. 
Mixed with gutta-percha this gum is practically indestructible. 
The name "Almeidina" is that of the first important shipper of 
the gum; in England the spelling "Almadina" has come into 
use. The gum is known also as " Euphorbia gum." Warburg 
and Jumelle say that Almeidina comes from Euphorbia rhip- 
saloides, which must not be confused with E. tirucalli. Berry- 
gives Almeidina 82.78 per cent, resin, and 9.40 per cent, hydro- 
carbon. 

Latex from E. lactiflua (Chili) contains 3.88 to 5.00 per 
cent, of caoutchouc and 31.9 per cent, resins reckoned on the 
dry substance. 

Amazonian Resin Rubbers. — The valley of the Amazon 
contains various trees and plants that are caoutchouc pro- 
ducers, but which are generally neglected, as the gatherers are 
seeking the more valuable Hevea or Castilloa. At the same 
time the latex of some of these plants has been referred to as 
being used to a considerable extent for adulterating Para rub- 
ber. Among these are mentioned the trees known under the 
native names of Amapa, Sucuba, Surva, Tamanguiro, Molango, 
etc. All of these show a marked percentage of resin in the 
milk. 

Antipolo Gum is being made from Artocarpus incisa (the 
breadfruit tree) in the Philippines. Antipolo is a town in the 
province of Luzon. 

Baka Gum. — Found in the Fiji archipelago. Comes from 
Ficus obligua (Foret). Used by natives for birdlime. Milk very- 
abundant. Gum little known. Samples sent to England were 
reported upon as being suitable for mixing. 

Banana Rubber. — Green bananas yield considerable latex, 
which is 95.7 per cent, water and only 3.9 per cent, rubber. 
It is easily coagulated by boiling. Made from Musa sapientum 
and M. paradisiaca. 

Barta-Balli. — One of the best known native trees in the 
Guianas. The milk of this tree is sometimes mixed with Balata 
milk and is said to give it its reddish tint. The gum when dried 



BEIRA RUBBER— CHICLE 35 

by evaporation is rather sticky and soft, but when precipitated 
in alcohol is dry and firm. Reports from England are rather 
condemnatory as the gum is said to absorb a great deal of water 
in washing, which it retains very obstinately. The same gum, 
dried by precipitation by spirits of wine, is said to be very 
brittle. Known also as Cumaka-balli. 

Beira Rubber. — Another name for stick rubber, gathered 
on the East Coast of Africa, and shipped from Beira. 

Canoe Gums. — From the bark of the breadfruit tree, which 
is found so plentifully in the islands of the Indian archipelago, 
comes a thick mucilaginous fluid which hardens by exposure 
to the air. When boiled with coconut oil it makes a tough, 
rubber-like substance, wholly waterproof, and very lasting. It 
is used ordinarily for waterproofing seams of canoes, pails, etc. 
It is also used when fresh, as a birdlime. Is probably from the 
Artocarpus integrifolia. 

Cattimandu Gum. — Derived from an Euphorbia found at 
the Cape of Good Hope. The juice is so acrid as to give in- 
tense irritation to any part of the body with which it may 
come in contact. The gum has been used as an anti-fouling 
dressing for ships' bottoms, but is little known otherwise. 

The natives use the milk as a cement to fasten knives in 
their handles. Under the influence of heat it becomes soft and 
viscid and when dry is very brittle. It is probably about as 
useful as Indian gutta. Found in Vizagapatam, India. Cat- 
timandu gum seems to be from Euphorbia trigona. 

Cativo Gum. — This comes from a tree called "Cativo" 
found in Central America and the United States of Colombia. 
The gum is fluid at 130 degrees F., and if the temperature be 
raised to 212 degrees F. it is easily filtered, impurities are re- 
moved, and a somewhat objectionable smell is greatly lessened. 
The gum is then of a clear reddish-brown color. It mixes easily 
with rubber and is said to produce a very tough compound. 
When vulcanized with 5 per cent, sulphur, this gum makes a 
fine, elastic product. When vulcanized with more than 5 per 
cent, sulphur, it becomes like gutta-percha, and can be sheeted 
or molded, when warmed. 

Chicle. — A gummy, resinous substance found in the Achras 
sapota, a tree growing abundantly in the warm, damp regions of 



36 LITTLE KNOWN RUBBERS 

Mexico, and also in portions of Central America. Chicle should 
be of a whitish color, odorless, and free from impurities, 
but often is adulterated with an inferior pink or reddish soil. 
It is solid and brittle at ordinary temperatures, but becomes 
plastic when placed in hot water. It is quite soft at 49 de- 
grees C. (120 degrees F.). It is used chiefly in the United 
States in the manufacture of chewing gums, and to a small 
extent in England for adhesive plasters. It has been used for 
modeling purposes and for mixture with india rubber for in- 
sulation work. The fruit is about as large as an apple, though 
looking more like a quince and is eaten under the name of 
"sapodilla" or "sapotilla" plum. The fruit is pricked or sliced 
and the latex is allowed to ooze out without squeezing, so as 
not to get the other juices. Lateral tapping is used on the 
tree, and 15 to 25 pounds of milk or 5 or 6 pounds of gum 
may be obtained in one season without injuring the tree. The 
milk is coagulated by boiling. Prolonged boiling makes it 
reddish, though some trees are said to yield a red gum. The 
best chicle is made from highland grown trees. The trees some- 
times grow 70 feet high, and the wood, which is very heavy, 
takes a high polish and is quite valuable. The analysis of 
chicle shows 44.80 per cent, resin, 17.20 per cent, rubber, 9 
per cent, water, and 8.20 per cent, starch and other matters, 
on an average. It sometimes contains as much as 55 per cent, 
of resins when dry. 

Chicle is 60 per cent, soluble in acetone; the remainder 
can be powdered and has none of the characteristics of rubber. 

Coorongite. — Sometimes known as Australian caoutchouc. 
An india-rubber-like material, discovered first near Salt creek, 
a short distance from the coast of South Australia. It was 
first observed in little hollows of sand and resembled patches 
of dried leather, but it generally occurs in the swamps. It is 
supposed to be of the petroleum series. Some scientific au- 
thorities in England and America ascribe to it a vegetable 
origin and regard the gum as exuding from a plant or lichen. 
It is not soluble in the ordinary rubber solvents, but after mix- 
ing with india rubber it can be dissolved. According to Forster, 
it vulcanizes somewhat as india rubber does. 



COW TREE RUBBER— GUTTA-SHEA 37 

Cow Tree Rubber. — The cow tree is very plentiful in 
tropical South America and yields a milk commonly used for 
food. This milk contains considerable caoutchouc, which is 
about 30 per cent, resin. Botanically it is known as the Brosi- 
mum galactodendron. Besides Brosimum galactodendron, War- 
burg mentions another cow tree, Couma utilis, an Apocynacece, 
growing in northern Brazil, while B. galactodendron is an Arto- 
carpece of Venezuela. Couma utilis latex contains rubber, and 
is used by the natives in waterproofing. Cow tree milk is ex- 
ceedingly hard to coagulate, and evaporation product is com- 
pletely soluble in hot acetone, seeming to indicate absence of any 
rubber. The constituents are mainly fatty matter, possessing 
neither tenacity nor elasticity, according to the German chemists. 

Cumai Rubber. — From the milk of a tree found on the 
Rio Negro and Uaupes, in Brazil. None comes to market. 
This milk is used by the natives for waterproofing purposes. 

Goa Gum. — This is a gum that comes from the Mival- 
cantem, which grows wild in the Coucan district in Brazil, 
and is also planted for hedges. Chocolate in color, softens 
under heat, is easily molded, and thoroughly waterproof. 

Gutta-Bassia. — Found between Upper Senegal and the 
Nile. Has the appearance and apparently many of the proper- 
ties of gutta-percha. Softens in warm Vater and becomes 
glutinous at the boiling point. Is soluble in sulphide of car- 
bon, chloroform, benzole, and alcohol. Can be kneaded in 
water as easily as ordinary gutta. It may be the same as Karite 
gutta, which is from Bassia Parkii, though there are other 
African Bassias which are said to yield good gutta. 

Gutta-Grek. — A gum that comes from Palembang, in 
Straits Settlements. It appears very much like india rubber 
but is permanently softened and destroyed by heat sufficient 
to melt it. It smells like gutta-percha rather than india rubber. 

Gutta-Horfoot. — This is a vegetable juice sent in sealed 
tins from the Straits Settlements, which yields a material like 
india rubber of fair quality. No way of coagulating the juice, 
where it is gathered, seems to be known. 

Gutta-Shea. — Said to be the nearest approach to gutta- 
percha among African products; obtained from the Shea, 



38 LITTLE KNOWN RUBBERS 

Galam, or Bambouk rubber-tree (Butyrospermum Parkii). The 
butter is the solid fat contained in the seeds and is used in 
making hard soaps. Gutta-shea is separated from the fat in 
the course of the soap making and is found to be present to 
the extent of from 5 to 75 per cent. A kind of gutta-percha 
is also obtained from the trunk of the tree in small quantities. 
Also known as " Karite gum." Analysis of the butter shows : 
guttalike 25.20 per cent.; resin 57.13 per cent.; water 5.04 per 
cent. ; impurities 12.63 per cent. The yellowish butter smells 
and tastes much like cocoa butter. Cazalbo claimed to have 
differentiated two varieties, one yielding a red and the other 
a yellowish gum. The red kind is the more valuable, and this 
tree also yields gum from its trunk, while the yellow gum 
tree does not. It is uncertain whether the yellow butter yields 
any gutta, though the trunk gutta from the other variety is 
comparable to Red Borneo in toughness and in its structure. 
Called also "Karite gutta" and "Shea butter." Knowledge 
on this subject is still confused and the authorities conflict. 
The two varieties are called " Shea " and " Mana," the Shea 
being the one which yields gutta, and also the more abundant 
variety. The branches seem to yield even more than the trunk. 
The milk is allowed to stand in the open air for about 24 
hours, when it partially curdles. The crystalline particles are 
then kneaded into a mass in hot water. However, reports on 
this gum are conflicting, and it is probable that two sources 
are confused. Some advices seem to point to the plumb-like 
fruit as the source of both gutta and butter. Fendler and 
Heim consider Karite gutta worthless as a substitute for gutta- 
percha. 

Gutta-Susu or Borneo No. 3. — Also called "gutta grip," 
at Singapore, and formerly known as "Assam white." The 
washing loss is 30 to 45 per cent., and the clean rubber con- 
tains 14.5 per cent, resin. In Java and Sumatra it is generally 
stored under water. The vine is tapped and the gum left to 
dry on the bark. The milk is sometimes gathered and coagu- 
lated with salt and boiling, but this method is not so good 
as bark drying. It is white and remains so under water, but 
darkens on exposure to the air. 



INDIAN HEMP RUBBER— MUDAR GUM 39 

Indian Hemp Rubber (Apocynum). — Coagulation of latex 
is spontaneous, yielding about 33 per cent, of coagulum, con- 
taining 4 per cent, of low-grade, black, soft rubber. 

Jelutong. — See Pontianak. 

Jeve, Jebe, or Heve (hence Hevea) was the ancient name 
for rubber among the natives of Ecuador. The name was ap- 
plied to a rubber coming principally from the neighborhood of 
Iquitos, Peru. (See Peruvian rubber.) 

Jintawan. — A bastard gutta-percha mentioned by Thomas 
Hancock in four patents and also by Taylor and Duncan. 
Probably a mis-spelling of " Djintaan soesoa," the same as 
gutta-susu. 

Loranthus Rubber. — A sticky non-elastic Venezuelan 
product. Contains 18 per cent, of resin. 

Maboa Gum. — Said to be produced from a species of 
Ficus in Santiago de Cuba. 

Macwarrieballi Gum. — A rubber gathered in British 
Guiana from the Forsteronia gracilis. From the report of the 
director of the Kew gardens, to whom a sample was submitted, 
it would seem that, while the gum is at present unfit for use 
in place of ordinary caoutchouc, because of its stickiness, it 
might be of value in cements, frictions, and the like. Forster- 
onia gracilis is a vine or bush rope belonging to the Apocynacea. 
The milk appears to be often mixed with that of balata or 
Bartaballi, though Macwarrieballi is more like rubber than 
balata. The vine is very rich in latex. 

Mangegatu Gum. — This comes from Vizagapatam, India, is 
a gum of the bastard gutta type, and is said to come from the 
Ficus Indica. 

Mandarnva Rubber. — A low grade of South American 
gum, somewhat like Ceara rubber. Little known. Is said to 
grow on the dry arid uplands of the interior. Is one of a 
number of gums that bear the native names, " Cauchin," " Pau," 
and " Massaranduba." 

Manga-Ice Rubber. — Argentine republic. It is very abun- 
dant. Produces good rubber. 

Mudar Gum. — This comes from an Asclepiad, commonly 
known as gigantic swallowwort (Calotropis gigantea). The 



40 LITTLE KNOWN RUBBERS 

shrub is found throughout the Southern provinces of India 
and grows to a height of from six to ten feet. Produces a 
gutta-like substance, which becomes plastic in hot water, and 
in other ways acts somewhat like gutta-percha. It insulates 
badly, but is recommended for waterproofing. Analysis : Rub- 
ber, 16.92 per cent. ; rosin, 83.08 per cent., according to War- 
den (1885). Hooper found 25.54 per cent, of a rather poor 
rubber, and 62 per cent, resin. 

Musa Gum. — A gum expressed from the peel and leaves 
of the banana and pisang plants. No gum yet on the market. 
Process patented in England by Otto Zurcher, of Kingston, 
Jamaica. Also called "banana rubber" (which see). 

Namaqualand Rubber {Euphorbia drageana). — A new 
source of rubber growing wild in the uplands of Namaqualand, 
South Africa. It is said to yield 17.6 per cent, pure rubber and 
70 per cent, resin. 

Neen Rubber. — A rubber-like gum said to be produced by 
an insect, reported from Yucatan. The insect belongs to the 
coccus family, feeds on the mango tree, and swarms in those 
regions. It is of considerable size, yellowish brown in color, 
and emits a peculiar oily odor. The body of the insect con- 
tains a large proportion of grease, which is highly prized by 
the natives for its medicinal properties in skin diseases. When 
exposed to great heat, the lighter oils of the grease volatilize, 
leaving a tough wax which resembles shellac. When burnt this 
wax produces a thick semi-fluid mass, like a solution of india 
rubber. An "ant wax" or lac is found in Madagascar and is 
secreted by two insects, Gascardia Madagascariensis and Gas- 
cardia Perrieri. The former secretes a white gum, containing 
52 per cent, of resin. The latter secretes red gum, with 46 to 
48 per cent, resin. The two gums have the same value. 

Ocotillo Rubber. — A plastic extracted from the ocotillo 
plant (Fouquieria splendens), a. shrub common to Texas, Ari- 
zona and Northern Mexico. 

Pala Gum. — Found in Assam and Ceylon. The wood and 
the bark are valued in India for their medicinal qualities. The 
tree yields an abundant milky juice, which after coagulation 



PALO AMARILLO—TALOTALO GUM 41 

acts something like gutta-percha. It readily softens in hot water 
and takes impressions, which are retained when cold. Also 
known as " Indian gutta-percha." Comes from the Dichopsis 
elliptica. It has been used as an adulterant of Singapore gutta 
for some years. It was used also as birdlime or cement and 
keeps well under water. Is hard and brittle when cold. The 
resin is easily removed by boiling alcohol, and the residue ap- 
pears to be a very fair gutta. 

Palo Amarillo. — A varnish-like gum from the latex of 
the Mexican tree Euphorbia fulva. Analysis of the latex gives 
34 per cent, gum and 6 per cent, resin. So far the gum is not 
susceptible of vulcanization and is not elastic. 

Palo Colorado. — A Mexican grade derived from the tree 
known as polo Colorado in the state of Durango. 

P. F. U. — A good rubber, not now obtained commercially, 
the source of which was the Colorado desert weed, the Picra- 
denia floribunda utilis. 

Pickeum Gum. — See Guayule. 

Sarua Rubber. — Found in the Fiji archipelago, from Alsto- 
nia plumosa. Formerly collected largely, but little comes now 
to the market. Natives take no interest in its collection. The 
juice comes from the stems and leaves but not from the trunk 
of the tree. It is soft at first but coagulates almost at once, 
hardens after a time, and becomes inelastic, of about the color 
and consistency of putty. It is gathered by the natives during 
a season of three months. 

Seiba Gum. — See Tuno. 

Susu-poko (meaning English tree milk). — A gum from a 
tree growing in the Malay peninsula, used in the place of gutta- 
percha, after being cleansed and treated with chloride of sul- 
phur. Mentioned by Leonard Wray in 1858. 

Talotalo Gum. — Found in the Fiji archipelago. Comes 
from Taberncemontana Thurstoni. The gum is hard, gutta- 
like, and without elasticity. Also called " Kau Drega." The 
milk is thin, but the tree grows large, up to two feet in diameter, 
and it is the best rubber source in the Fiji islands. 



42 LITTLE KNOWN RUBBERS 

Talaing Rubber. — An almost black rubber which, when 
cut into, is white and porous, presenting a honeycombed ap- 
pearance, the cavities being filled with a watery fluid. It is 
quite tough and elastic and appears to be of good quality. It 
comes from a creeper which is abundant in the Philippines, 
in Malacca, and Indo-China. The juice is very abundant, and 
is coagulated by being boiled in water. 

Tirucalli Gum. — This is a Euphorbium gum, from the 
Indian plant known as milk hedge. The milk of this plant is 
used for various purposes, chiefly medicinal, in India, and has 
been suggested as a substitute for gutta-percha. Like gum 
Euphorbium, it has a very acrid character, and the collection 
of it is a very dangerous operation to the eyes. When dry it 
becomes very brittle, but when warmed in water is quite elastic. 

Touchpong Gum. — It is found throughout the Guianas. 
Probably from Sapium biglandulosum. Spelled "touchpong" by 
Jenman; "touchpong" by Morris; "pouckpong" by Dr. Hugo 
Miller. The rubber dries in strips on the trees, and what little 
of it comes to market has not been recognized as a distinct sort. 
Samples sent to England, however, have been favorably re- 
ported on. 

Analysis of touchpong gum by the Imperial Institute, Lon- 
don, gave 93.7 per cent, rubber and 1.8 per cent, resin. 

Tu Chung Rubber. — This is an interesting gum derived 
from the Eucommia ulmoides, or the chung tree, native of China. 
It has been definitely established that this tree can be readily 
acclimated in temperate countries. 

Tuno is a trade name applied to a gum gathered princi- 
pally in Nicaragua and Honduras. It is the product of what 
has been called the "sterile rubber tree" and also the "male 
rubber tree" of Nicaragua. The milk is coagulated with the 
aid of heat. The gum is but slightly elastic, is very sticky 
when heated, and is cheap. It is used as a friction gum, and 
is also mixed with balata in the manufacture of belting. Some- 
times it is sold under the name of " Seiba gum," its identity 
being lost by ingenious massing and manipulation under water. 
Nicaragua rubber adulterated with "Tuno" in coagulation soon 



YELLOW GUTTA 43 

hardens and loses its elasticity. Also spelled " Toonu " and 
" Tunu." It is derived from Castilloa tunu, and called locally 
"caucho macho" or male rubber. Though it has a bad repu- 
tation, Mr. E. Poisson has drawn excellent rubber from this 
same tree in Costa Rica. Tuno gum usually runs over 80 per 
cent, resin. Berry gives it 80 to 86.13 per cent, resin, and 3.50 
to 7.06 per cent, hydrocarbons (gutta-like). 

Yellow Gutta. — This comes from the Sunda Isles, from 
the genus Payena. It is practically a compound of india rub- 
ber with two resins. One of these is crystallizable and the 
other is pitchy. If the raw material be treated with boiling 
alcohol the resins are taken off and the remaining product ap- 
pears to be good india rubber. Berry describes yellow gutta 
as " a gum of dual composition containing the hard resins 
characteristic of chicle, and the elastic caoutchouc-like hydro- 
carbon characteristic of rubber." It is more like rubber than 
gutta. The analysis gave 80 per cent, resin and 12.58 per cent, 
hydrocarbons (rubber?). The resin looks like chicle resin, and 
has a saponification value of 104.1, with a trace of acid. How- 
ever, there are several guttas which are yellow. 



CHAPTER III. 

COAGULATION OF RUBBER LATEX. , A , 

With the advent of the chemist in the rubber factory an 
exact knowledge of the various treatments to which india rub- 
ber may be subjected in forest or plantation is not only inter- 
esting but often of the greatest value. For this reason the 
following review of coagulating processes and systems is given 
at some length: 

Rubber latex is a mixed suspension and solution of rubber 
globules, resins, nitrogenous bodies (albumens or proteins), and 
saline substances contained in a watery medium or serum. 

Typical Hevea undiluted latex from Malaya (average from 
100 ten-year-old trees by Beadle and Stevens). 

Per cent. 

Rubber 35.62 

Resin 1.65 

Proteins 2.03 

Mineral Matter 0.70 

Water 60.00 

100.00 

The proteins are in colloidal solution and are capable of 
being precipitated by certain reagents, notably acids. Latex 
being a combined solution and suspension, has many of the 
characteristics of a colloidal solution. It seems probable that 
the protein acts as a protective colloid to the pure caoutchouc 
present due to the adsorption of a layer of the dissolved pro- 
tective agent over the surface of each of the suspended rubber 
particles. 

Four well-defined stages in the degree of coherence of 
rubber separated from latex have been noted by a writer in 
the " Tropical Agriculturist," namely : 

1. Creaming is the condition observed in the early stages 
of slow coagulation. 

44 



SMOKING 45 

2. Flocculence refers to the formation of small particles 
of rubber without coalescence into lumps. This state is ob- 
servable in latex to which much formalin has been added. 

3. Agglutination, or local lumpy coagulation, observed 
when latex coagulates spontaneously, or when certain mineral 
salts are added. 

4. Coagulation proper is the final stage observed on care- 
ful addition of acids to latex, the rubber forming in one clot 
and leaving a clear liquid. 

The purpose of coagulation is the separation of the rub- 
ber substances from the watery or serum portion of the latex. 
The differences between unlike grades of rubber are due partly 
to chemical composition, and also in a measure to varying 
methods of collection and coagulation. It is undoubtedly true 
that no one method of collection would be best for all kinds 
of rubber gathered, even if it were possible. It is important 
to the rubber manufacturer to know what systems are pursued, 
and particularly what ingredients are added, to produce coagu- 
lation, that he may standardize his compounds in respect to 
rubber quality. 

There are four basic methods of coagulating rubber latex: 

1. Smoking. 

2. Drying. 

3. Separation by chemicals. 

4. Mechanical separation. 

Smoking rubber is the system with which the world at 
large is most familiar, and is practised in the Amazonian for- 
ests in the collection of Para gum. Several kinds of palm nuts 
are used to produce a thick smudge, but those preferred are 
from the Urucuri palm {Attalea excelsa). This smoke has been 
found by analysis to consist mainly of acetic acid and creosote, 
the latter being a well-known preservative of rubber. Fine 
Para rubber is nearly always smoked in this way. Coarse Para 
is air dried. There are also trees found in the forests where 
it is impossible to get palm nuts, the wood of which is used 
successfully for the coagulating smoke. 

Smoke fumes, in addition to their coagulating action, exert 
a preservative effect by impregnating the coagulated gum with 



46 COAGULATION OF RUBBER LATEX 

creosote and formalin. Coagulation by smoking evaporates a 
considerable portion of the water contained in the latex. The 
temperature of the smoke close to the rubber in the native 
smoking of wild Para is about 160 degrees F. 

Dry Coagulation — Heat, Air, Sunlight. — Various rub- 
bers are coagulated simply by the exposure to slight artificial 
heat, to the sunlight, or merely to the air. Such are the coarse 
Para rubbers, certain of the Centrals, African, and East Indian 
rubbers. Fiji rubber is coagulated in the mouths of the natives, 
and some Angola rubber by evaporation on the arms and breasts 
of the natives. 

Some kinds of rubber dry directly on the tree and are 
removed in the shape of rubber threads compressed into large 
lumps or wound. Scrap of all descriptions of rubber is gen- 
erally obtained in wild and plantation culture through drying, 
in many cases with the help of chemicals. There is also, in 
some cases, simultaneous addition of certain decoctions (such 
as tannic acid, soap, salt, etc.). An important drying process, 
in conjunction with the use of chemicals is the Leva process, 
discovered by Dr. Hindorff and used in the production of plan- 
tation Manihot rubber. In this process the tree is previously 
coated with the extractive chemical solutions, the bark is next 
cut with a rounded knife. The latex which exudes coagulates 
while running down and is gathered from the trunk. 

A direct tannin drying process, first defined by A. Schulte, 
for Funtumia (Kickxia), is operated as follows: 

Funtumia latex is poured into a pan and sprinkled with 
tannin solution. The vessel is shaken and soon the mass can 
be turned in the mold like a pancake. The uncoagulated side 
is then sprinkled with tannin and the movement continued. 
Finally the cake thus formed is squeezed through a wringer to 
extract the water. 

Separation by Chemicals. — Many chemicals exercise a 
separating influence in the extraction of rubber from the latex. 
The first collectors of wild rubber used these influences as 
they exist in the form of smoking and plant juices, as well as 
in soaps and salts; also in the natural forms of perspiration, 
saliva and urine. 



MECHANICAL SEPARATION 47 

It was at first thought that the action of acids upon coagu- 
lation was only due to the insolubility of the albuminoids con- 
taining the globules of rubber. M. Henri has since shown that 
with latex freed from its salts or crystalloids, acids do not pro- 
duce complete coagulation, but only the agglutination of the 
rubber. In ordinary Hevea latex all acids produce coagulation, 
but the proportions of organic acids needed for that result are 
larger than in the case with mineral acids. The former are 
preferred on account of the corrosive action of the latter (such 
as sulphuric, nitric or hydrofluoric acids) upon the impurities 
which remain in the mass, as well as upon the metallic portions 
of the plantation factory plants. 

With respect to albumen, Dr. Frank concludes regarding 
chemical means of coagulation: 

1. All agents which precipitate and denature albumen 
operate toward separating the rubber. 

2. Separating agents which exercise a decomposing influ- 
ence upon the accompanying albuminous substance, or lead to 

its decomposition, require in addition to the coagulating agent, 
the simultaneous presence of preservatives. Substances which 
do not exercise such a decomposing effect can be used by 
themselves. 

Mechanical Separation. — The real mechanical method 
for removing the rubber substance from the latex is the cen- 
trifugal system by which a centrifugal machine removes the 
watery contents and produces a marvelously clear elastic rubber. 
This process is particularly suitable for Ficus latex. It also 
seems adapted for Hevea latex, but in the latter case acid should 
be added previous to the centrifugal action. 

A mechanical process of separation used on a large scale 
in the Dutch colonies, for the coagulation of Ficus latex, con- 
sists of subjecting the strained latex to the action of a beater 
or twirling rod. The addition of the thickened, creamy portion 
from latex which has been standing, materially hastens the sepa- 
ration and renders the process practical. 

Another mechanical process is that of Professor Daner for 

Castilloa, in which foreign substances, particularly those of an 

albuminous nature, are separated by dilution. 



48 COAGULATION OF RUBBER LATEX 

The following descriptions embrace the ordinary materials 
employed for coagulation as well as certain patented machines 
and processes. 

Amole Juice. — A native process for coagulating the milk 
of the rubber tree, which prevails throughout Central America, 
involves the use of an alkaline decoction made from the juice 
of a plant called "achete" or "coasso" (Ipomcea bona-nox, Linn., 
and also Calonyction speciosum). This is combined with rub- 
ber milk in the proportion of 1 pint to \y 2 gallons of the latter. 
During coagulation the vessels are often heated from 165 de- 
grees to 175 degrees F. After coagulation, the rubber is dried 
for twelve to fourteen days. The kinds of rubber coagulated in 
this fashion are Mexican, Nicaraguan, and in fact almost all of 
the rubbers that come under the head of Centrals, and are 
obtained from the Castilloa elastica. 

Acetic Acid. — Used in coagulating Hevea latex in the Far 
East. This acid, originally suggested by Perkins in 1898, is 
now used for coagulation in about 98 per cent, of plantation 
rubber produced. 

Alcohol. — One of the best general coagulants, but too 
costly to be commercially available. 

Alum. — This is used all through the Isthmus of Panama, 
and in coagulating Accra rubbers and other African sorts. 
Pernambuco rubber is also treated with a water solution of 
alum, as is the Nicaraguan at times. 

Bosanga. — The juice of the Costus afer, a seed used in the 
coagulation of the latex of Landolphia in the Lopori district 
in central Africa. 

Coconut Water. — Fermented coconut water has been 
found to be a cheap, satisfactory substitute for coagulating 
Hevea latex in place of acetic acid. 

Coyuntla Juice. — This is an astringent juice made from 
the Mexican weed of that name. When the rubber milk is 
gathered, it is placed in earthenware vessels and whipped with 
the weed, which causes coagulation. The Mexican rubber known 
as Tuxpam is treated in this way. 

Formic Acid. — Used instead of acetic acid in coagulating 
Hevea latex. 



HELFER PROCESS— SERINGUINA 49 

Helfer Process. — This consists of the addition of a solu- 
tion of acetic acid, and is based on the knowledge derived from 
the analysis of the smoke of the Urucuri nuts. 

Koalatex. — A proprietary preparation used in Ceylon and 
the Federated Malay States for coagulating the latex of the 
Hevea Brasiliensis. 

Lime. — A final process in the coagulation of rubber in 
India is the washing over with lime. Collins also mentions 
the use of lime in connection with the coagulation of Para 
rubber. 

Lime Juice. — Lagos rubber and some other African sorts 
are coagulated by the addition of a little lime juice, which is 
added as the milk flows from the vine. 

Nipa Salt. — A salt obtained by the burning of the plant 
known as the Nipa fruticans. It is used in the coagulation of 
Borneo rubber. 

Machacon Juice. — Cartagena rubber, which is gathered 
carelessly, is coagulated in a hole in the ground by the addition 
of the juice of the foot of the "machacon" — a strongly alkaline 
solution. 

Pozelina. — A preparation intended to keep rubber latex 
in a fluid condition until the time of curing. The ingredients 
used in making the preparation are secret. The headquarters 
for its sale are at Para, Brazil. 

Purub. — Another name for hydrofluoric acid, when pre- 
pared as a coagulant of rubber latex. 

Salt. — Many kinds of low-grade rubber are coagulated by 
the addition of salt or brine. Borneo, for instance, is coagu- 
lated in that way. Madagascar rubber receives a treatment of 
salt-water. Mangabeira rubber is treated with a mixture con- 
sisting of 1 part of salt to 2 parts of alum. Nicaragua rubber 
is also often coagulated with salt. 

Seringuina. — A chemical product for retarding for any 
length of time the coagulation of rubber latex. Is said to con- 
tain no corrosive elements. When the latex is finally smoked 
the substance evaporates entirely. It is the invention of Dr. 
Cerqueira Pinto, of Para, Brazil. 



50 COAGULATION OF RUBBER LATEX 

Soap and Wood Ashes, — The medium-grade rubbers all 
through Central America are often coagulated by the use of 
soap, and where that is not plenty, of a strong lye from wood- 
ashes. 

Spirits of Wine. — This is used sometimes in the coagu- 
lation of balata. 

Sulphur Fumes. — According to James Collins, rubber of 
the Para varieties is sometimes exposed to the action of the 
fumes of melted sulphur, which affects coagulation. This 
process, however, is very rarely followed. 

Torres System. — In addition to the natural methods de- 
scribed above, there are several that give some evidence of an 
intelligent study of the milk and the substances best adapted 
for this work. Under the Torres system a liquid is made by 
a secret formula, from the roots and fruits of certain South 
American palms, which, when added to the milk, preserves it 
from curdling, so that it will keep for weeks. It can thus be 
transported to a convenient place for smoking. 

COAGULATING MACHINES. 

Beta Separator. — The invention of Mr. John Hinchley 
Hart, F.L.S., of Trinidad. This is an arrangement by which 
the latex placed in the upper compartment is washed, filtered, 
and coagulated. The machine known as the Beta separator 
works somewhat on the principle of the cream separator. 

Coutinho's Machine. — This is a wooden cylinder about 
20 inches in diameter, set horizontally, revolving by a crank 
and so arranged that smoke is let into the inside through the 
cylinder shaft. The latex, by the revolution of the cylinder, is 
distributed over its inner surface and there smoked and coagu- 
lated. 

Danin's machine for smoking rubber is a revolvable cylin- 
der, through openings in the end of which smoke is forced, 
the latex first having been introduced through the other end of 
the cylinder. The cylinder being rotated, the latex spreads 
itself over its inner circumference and is carried past the dis- 
charge end of the smoke conduit and thus coagulated. The 
machine is the invention of J. R. C. Danin, of Para, Brazil. 



FUMERO—WICKHAM'S MACHINE 51 

Fumero. — A machine patented by G. van den Kerckhove, 
of Brussels, Belgium. The apparatus is simple, the latex being 
guided by the hand over the smoke and the rubber produced 
in ball form uniformly cured. The apparatus designs to do 
scientifically exactly what the Amazon rubber gatherers do 
crudely in smoking Para rubber. 

Frank-Marckwald Process. — This process is based on 
the simultaneous employment of dilution and heat, in conjunc- 
tion with suitable chemicals. It is founded on the injection 
of latex in a thin jet into a much larger quantity of boiling 
water. The separated portions almost immediately thrown off 
are taken out of the water, rinsed, and drawn through rolls 
to remove the contained water preparatory to drying. 

Suitable acids are recommended for various kinds of rub- 
ber (such as citric and hydrofluoric) ; formalin is specially 
recommended in connection with Funtumia. These acids are 
previously added to the diluted latex. The active principle in 
this process is the rapid and intense solidification, while the 
albumen is at the same time separated. 

In Dr. Frank's opinion, this process is the most satisfac- 
tory yet invented for Funtumia and Ficus, as well as, so far 
as experience goes, for Manihot latex. The latter coagulated 
in East Africa on a different system, has not produced satis- 
factory qualities of rubber. 

Da Costa's Smoking and Coagulating Apparatus. — 
Smoke containing a small amount of acetic acid and creosote 
is obtained by a wood fire in the furnace of the apparatus, 
from green palm leaves, nuts, etc. These fumes are held in 
a special receiver from which they are forced by a steam in- 
jector into the coagulating tank. The latex is thus thoroughly 
agitated and mixed with the smoke. The completely coagu- 
lated rubber can be 'removed in a short time. 

Wickham's Machine consists of a horizontally revolving 
cylinder adapted to hold the rubber latex and expose it in a 
thin layer to the action of smoke which is directed against it. 
The smoke is produced in a furnace by burning the oily nuts 
of palms with charcoal and is injected into the coagulating 
cylinder at a point sufficiently above the level of the latex in 



52 COAGULATION OF RUBBER LATEX 

the cylinder to enable each fresh film to form evenly before 
it arrives in front of the smoke jet. Other suitable agents 
may be used in place of smoke. 

Electric Coagulation. — Coagulation of rubber latex by 
electricity has been successfully performed on plantations where 
acetic acid was scarce. This coagulation is effected in a porous 
vessel with carbon electrodes, using a low tension current. The 
latex is slightly diluted with water and the gum separates very 
rapidly. It is perfectly clear and limpid. 

CAUSE OF COLOR IN CRUDE RUBBER 

The darkening of smoked Para has been demonstrated to 
be caused by an oxydase or oxidizing enzyme present in the 
latex and its action on certain oxidizable substances naturally 
present in the latex, but which may be added to by the smoke. 

Dr. David Spence has made some very profound and 
practical researches on the matter of the darkening of rubber 
on exposure to the air and his description of the enzymes caus- 
ing this effect is here appended: 

"These enzymes are probably, as I learned, present in the 
protein of the latex of all rubber-producing plants, and so act 
upon the insoluble portion of the protein that it is converted 
into colored products, which impart the dark color to the rub- 
ber. In my original work I determined that the temperature 
at which the oxidizing enzymes are destroyed lies very close 
to the point where in general other similar enzymes perish. 
To obtain rubber only slightly darkened, it seems, at first 
glance, only necessary to destroy the active enzymes in the 
latex or the rubber by heating above the sterilizing tempera- 
ture, 75 degrees C. But this method of destroying the enzymes 
by means of heat is not so easily accomplished in practice, and 
this fact leads me to the belief that in the latex and in the 
rubber there was a heat-resisting agent, zymogen, which slowly 
changed into active enzymes. 

"I found, for example, that freshly cut pieces of Para 
rubber, washed thoroughly with water for more than an hour 
to remove the strongly colored soluble matters, gradually dark- 
ened and after exposure to the air finally became entirely black. 



COLOR IN CRUDE RUBBER 53 

Potassium cyanide, a mercury chloride solution or acetic acid, 
failed to prevent the dark coloration, or at least after the above 
solutions were completely removed by washing. I made many 
experiments with the latex of Funtumia elastica, but found with- 
out exception that heating the latex of the rubber prepared there- 
from even to 100 degrees C. for half an hour was insufficient 
to alter the tendency to turn dark. 

"It is known that certain natives on the West African 
coast obtain rubber from the latex of Funtumia elastica by heat- 
ing it with water until the separating rubber particles coalesce 
into balls. Nevertheless, I have seen no sort of rubber pre- 
pared in this manner in which the effect of the active oxydase 
enzyme was not plainly observable. 

"Since the oxidizing enzyme is very stable towards heat, 
the best method for handling the latex to secure only faintly 
colored rubber appears to be the one presented previously by 
me and now repeated here. By this method the enzyme itself 
is to be removed as completely as possible before coagulation. 
The latex is diluted with water before the coagulation and the 
agglomerating rubber particles washed well (this applies at 
least to Funtumia elastica) in order to remove the oxidizing 
enzyme as well as other foreign matter from the rubber. In 
this manner a snow-white rubber is obtained. Yet to prevent 
as much as possible the baneful effects when using the boil- 
ing process a substance having a noxious action against the 
enzyme but a harmless one towards rubber could be utilized." 

Subsequent to these observations of Dr. Spence, the re- 
searches on this problem by Beadle and Stevens resulted in the 
discovery that the addition of one part of sodium bisulphite to 
500 to 1,000 parts of latex neutralizes this enzyme with the 
result of producing a permanently very pale rubber. This treat- 
ment is without injury to the rubber quality and is particularly 
adapted to white and transparent goods. 

It should be remarked that color is not an indication of 
quality; also the defects of appearance arising from various 
causes and known as oversmoking, have nothing to do with 
quality, and the same is true of the appearance of small bubbles 
in the sheet. 



CHAPTER IV. 

VULCANIZING PROCESSES AND INGREDIENTS- 
PLANTATION HEVEA AND THE OPTIMUM 
CURE. 

The means for vulcanizing india rubber in general use are 
roughly two: the heat cure and the cold cure. Considering 
the first, a great variety of goods is cured in open steam heat 
and is kept in shape during vulcanization, either in molds or 
by being wound with strips of cloth or buried in pans of French 
talc. This is the wet heat and such goods are cured in vulcan- 
izers, big and little, of which there are many forms. A different 
application of heat is what is known as dry heat, where goods 
are put in a hot room without wrapping or mold protection, 
and left until vulcanization is effected. Another heat cure 
which at one time was very largely used, but to-day has prac- 
tically disappeared, was what was known as solarization. This 
consisted in exposing fabrics coated with a thin skim of rubber 
to the rays of the sun, which effected a surface cure. 

A special heat cure adapted to very particular work, such 
as curing pure rubber thread sheet, is the water cure. In this 
method the rubber receives the vulcanizing heat by immersion 
in water raised to the required degree. 

What is known as the cold cure has been practiced since 
the days of Goodyear, and within the last few years has been 
much resorted to in the manufacture of certain lines of goods. 
This in turn, divides itself into two methods — the acid and the 
vapor cure. In the former, one-half pound of chloride of sul- 
phur is mixed with four pounds of bisulphide of carbon. The 
goods are dipped in this solution and afterwards treated with 
an alkaline wash. The vapor cure is where the fumes of 
chloride of sulphur are set free in a heated room or cabinet in 
which the rubber goods are suspended so that all of the sur- 
face is affected. When the cure is far enough advanced the 

54 



EARLY INVENTORS 55 

further action of the chloride of sulphur fumes is stopped by 
ammonia fumes. 

While Charles Goodyear's patents for the vulcanization of 
india rubber by the use of sulphur and heat were in force, a 
marvelous amount of ingenuity was shown in the attempts to 
accomplish the same results by the substitution of other in- 
gredients for sulphur, either with or without the use of heat. 
These experiments and inventions embrace vulcanization, by 
means of chlorides, nitrates, nitrites, fluorides, bromides, iodides, 
and phosphorets of about all the common earths and metals, 
and also many gases such as sulphurous acid gas. The ma- 
jority of these experiments have been lost sight of, partly 
because the Goodyear process is now open to the world, and 
partly because, for the majority of goods, the sulphur and heat 
cure is not only the cheapest, but the easiest to accomplish. 
It may be well, however, to review and record the experiments 
in this line, as there is no doubt that for special lines in rubber 
manufacture many of them have a suggestive value today. 

One of the very first ingredients to which inventors and 
experimenters turned their attention was zinc. The veteran 
rubber manufacturer, Jonathan Trotter, described a process for 
preparing a vulcanizing material which he catted hyposulphite 
of zinc. It was made from a solution of caustic potash satur- 
ated with flowers of sulphur and then treated with sulphurous 
acid gas. This solution he mixed with a saturated solution of 
nitrate of zinc, forming the precipitate that he desired. He 
used 3 pounds of hyposulphite to 10 pounds of rubber, curing 
from 3 to 5 hours, at 260 degrees to 280 degrees F. 

E. E. Marcy, an American, some years later patented a 
compound of hyposulphite of zinc and rubber which is appar- 
ently almost identical with Trotter's discovery, although he 
disclaimed similarity, and also made public the process, in 
which he used a combination of hyposulphite of zinc and sulphide 
of zinc, the compound being 2 pounds of rubber, 1 pound sul- 
phide of zinc, 1 pound hyposulphite of zinc, and other ingredients 
as deemed necessary. These goods were of a beautiful white 
color, were said not to bloom, and did not need the sunning 
process then in use. At the same time they depended upon 
sulphur and heat for whatever vulcanizing was accomplished. 



56 VULCANIZING PROCESSES 

Another attempt to get a good substitute for sulphur was 
in the production of what is known as sulphite or hyposulphite 
of lead. James Thomas describes at length a compound in 
which he mixes hyposulphite of lead and artificial sulphide of 
lead in equal proportions, his compound being for vulcanization, 
2 parts by weight of india rubber and 1 part of the vulcanizing 
material. 

Following this thought came E. E. Marcy again, who mixed 
sulphide of lead and carbonate of lead in the proportions of 
2 parts of sulphide of lead, 1 part carbonate of lead, and 2 
parts protoxide of lead in place of the carbonate. 

Then Oscar Falke and Albert C. Richards brought out a 
compound consisting of 6 parts india rubber, 2 parts sulphide 
of antimony, and y 2 part sulphite of soda, curing at 270 de- 
grees to 280 degrees F. 

A. K. Eaton, in no uncertain terms, disclaimed vulcaniza- 
tion by the use of free sulphur, but claimed to be the first to 
use sulphide of manganese. He also gave a formula for mak- 
ing it, which was by mixing intimately 44 parts of peroxide 
of manganese with 32 parts of sulphur, and exposing the mix- 
ture to heat in a covered crucible. He vulcanized several hours, 
from 250 degrees to 310 degrees F. 

George Dieffenbach claimed sulphite of alumina as an in- 
gredient which, in connection with heat, would bring about 
vulcanization. He used this in a compound for a dental rub- 
ber, which had for its basis india rubber, amber, linseed oil, 
sulphide of cadmium, oxide of tin, vermilion, and pulverized 
feldspar. 

Charles T. Harris cured india rubber by combining it 
with an artificial sulphide of bismuth, which he explained as 
being the artificial tersulphide, or polysulphide of bismuth. 
He describes this as being a heavy black powder, and the 
compound which he advised for soft rubber was 100 parts 
india rubber, 75 parts carbonate of lead, and 12^ parts poly- 
sulphide of bismuth, cured in a dry heat at 245 degrees F. for 
\ x / 2 hours. 

Henry W. Joselyn discovered that shale combined by heat 
with sulphur formed a sulphide which could be used in curing 
rubber, and hastened to patent it. 



EARLY INVENTORS 57 

Andreas Willman brought out a process for combining 
india rubber with "anhydrous chlorides, sulphates of alkalies" 
and powdered coke or coal, and claimed that his best result 
came from chloride of ammonium and coke. His compound 
was made up of litharge, lampblack, and powdered coke, in 
connection with from 2 to 10 per cent, of his vulcanizing 
mixture. 

Edwin L. Simpson formed a vulcanizing compound by 
mixing benzoin gum with pulverized sulphur, and boiling it in 
linseed oil. It was used in a dry heat, the compound being 1 
pound of india rubber, 2 ounces vulcanizing compound, 8 ounces 
litharge, and 8 ounces whiting. 

J. A. Newbrough manufactured a vulcanizing material 
which he called acid resin, made of turpentine and sulphuric 
acid. This he incorporated in india rubber in the proportion 
of 6 ounces of acid resin to 1 pound of india rubber, and cured 
at 300 degrees to 320 degrees F. 

The use of selenium as a curing agent was discovered by 
E. E. Marcy, while connected with Horace H. Day, then 
prominent as a rubber manufacturer. He advised the use of 
equal parts of india rubber and powdered selenium, and, to 
produce a glossy finish, he added selenium carbonate and 
whiting. 

At the same time there were many other inventors who 
were experimenting with processes that were somewhat in the 
line of the well-known Parkes cold-curing process. For ex- 
ample, it is a matter of history that the late Joseph Banigan, 
early in his career as a rubber manufacturer, cured wringer 
rolls by an acid process. 

Dubois C. Parmelee invented a process which he called 
" hermizing," to distinguish it from curing or vulcanizing, in- 
stead of the Parkes process, in which the solution of chloride 
of sulphur and bisulphide of carbon was used. He recom- 
mended briefly a solution as follows : 10 pounds of coal-tar 
naphtha, in which was dissolved 1 pound of sulphur. Into this 
solution he passed dry chlorine gas until it assumed a fine 
yellowish-green color. This solution he used as a dip for such 
goods as would be cured by the acid treatment. Parmelee also 
claimed the discovery of a solution made of coal-tar naphtha, 



58 VULCANIZING PROCESSES 

bisulphide of carbon, and a solution of sulphur in bromine, 
mixed with this. 

R. F. H. Havermann reduced india rubber to a solution 
and subjected it to the action of chlorine. He also, in a later 
patent, described the washing of the chlorine out of the rubber 
by alcohol, and the addition of ammonia and lime, the result 
being, according to his specifications, a white, hard rubber. 

Working in the same line, John Helm, Jr., dissolved india 
rubber in benzine and mixed it with liquid chlorine in the pro- 
portion of 12 ounces of chlorine to 1 pound of gum. His claim 
was that he could get rubber of any color and of any degree 
of hardness by this process. 

H. A. Ayling patented a cold-curing process in which 
carbon spirits (naphtha), one of the petroleum series, was 
mixed with chloride of sulphur, instead of the usual bisulphide 
of carbon. 

In the line of hard rubber manipulation and vulcanization, 
L. Otto P. Meyer (then connected with, the India Rubber 
Comb Co.) patented a process for curing vulcanite in a vessel 
wholly or partly filled with water, the water in which the rub- 
ber was contained being in a tight receptacle, and the heat being 
raised above 300 degrees F., the pressure of the surrounding 
steam keeping it from vulcanizing. This obviated the danger 
of burning, and was of great value in the production of certain 
goods. 

While these and other inventors were trying to cure rub- 
ber without sulphur, and without interference with the Good- 
year patents, certain others were at work on other gums. For 
example, John Rider, who was at the head of a gutta-percha 
company, produced what he called mettalothyanized gutta- 
percha. In this, he first heated the gutta-percha, then mixed 3 
pounds of hyposulphite of lead and zinc with 8 pounds of gum, 
and sometimes added also a little Paris white, or magnesia. He 
then put the compound from 2 to 10 hours in a dry heat and 
cured it at 280 degrees to 320 degrees F. 

John Murphy changed this compound somewhat, by ad- 
vising the incorporation of sulphur in the proportion of 2 to 6 
ounces of sulphur to 10 pounds of gutta-percha. This sulphur, 
by the way, obviated the preliminary heating of the gutta-percha, 



EARLY INVENTORS 59 

which was supposed to volatilize the ingredients that had before 
rendered it unvulcanizable. 

William Mullee brought out a curious process for the 
manufacture of hard rubber. In this, just as soon as the rubber 
was washed, the sheets were immersed in the sulphur bath, 
heated to 220 degrees F. The water and other impurities in 
the rubber were said to be extracted by the action of the heated 
sulphur. After boiling 30 minutes, the sheets were removed 
and washed to prevent crystallization. They were then sub- 
jected to the same process a second time. The rubber was 
then compounded in the usual way, on rolls, the proportions 
being 17 to 24 ounces of sulphur to 16 ounces of rubber. The 
claim for this was that the compound when cured was tougher 
than any others ever known. 

William Elmer prepared what he called "elastic selenide 
of caoutchouc." He first dissolved the india rubber in bisul- 
phide of carbon, placed it under pressure, and heated gradu- 
ally. When brought to about 300 degrees F., the liquefied 
selenium was put into the apparatus drop by drop, the solu- 
tion in the meantime being kept in constant motion. This 
elastic selenide he claimed to be semi-fluid which, when evap- 
orated, possessed all the characteristics of india rubber. 

The Parkes cold-curing process is so widely known as to 
require but a word. It is based on the invention of Alexander 
Parkes, and depends upon the faculty that chloride of sulphur 
has for vulcanizing india rubber. Chloride of sulphur may be 
applied for vulcanization either as liquid or as vapor. 

A great many thin sheet rubber goods are cured by the 
vapor process. This is done in many cases by hanging the 
goods in an air-tight chamber, like a dry heater, and passing 
the vapor, which is either that of chloride of sulphur alone, 
or chloride of sulphur mixed with carbon bisulphide, into the 
curing room. Small articles are often put in a tumbling barrel 
made of wire, which revolves slowly in the vulcanizing room, 
thus giving the vapor a chance to do its work thoroughly. The 
rubber surfaces are of course dusted first, to keep them from 
adhering. Proof cloth is cured in vapor by passing the rub- 
ber surface over troughs in which this reagent is slowly 
evaporating. 



60 VULCANIZING PROCESSES 

Parkes also suspended articles to be vulcanized in a dry 
heater and passed the following gases into the chamber as a 
means of vulcanization: Sulphurous acid, gas, chlorine, nitrous 
acid, or the vapors of bromine or iodine. 

Charles Hancock cured rubber by the action of vapors 
produced by dissolving zinc, copper, or mercury in nitric acid. 
The action of these vapors being so active, only one or two 
moments were given, and the surfaces then washed in an alka- 
line solution. 

Nickels passed sulphur fumes and hydrogen into the gum 
while in a masticator, curing afterward by heat. 

Caulbry's process is similar to that of Parkes's, by which 
it is claimed rubber can be vulcanized at ordinary tempera- 
tures, by using an intimate mixture of chloride of sulphur and 
dry chloride of lime. During this mixture, and when the smell 
of the chloride of sulphur will be noticed, the temperature of 
the mixture will rise, the mass becoming plastic by the soften- 
ing of the sulphur. If a mixture of this kind, in which sul- 
phur is in great excess, be added to the solution of india 
rubber in bisulphide of carbon, the rubber will be vulcanized 
at an ordinary temperature, or perhaps with a slight warming. 
Chloride of sulphur used pure is too corrosive in its effect on 
india rubber; it is therefore reduced in all cases. Only thin 
articles can be vulcanized in this way. 

A patent taken out in England by Edmond Gamier re- 
lates to the vulcanization of india rubber by the use of alum. 
Previously alum processes for curing had not been very suc- 
cessful, but this patent had some novel features. It called for 
particularly dry alum treated with a solution of terebinth of 
benzol and shellac, or some similar gum. In use he took 8 
ounces of alum and a solution composed of 1 part gum and 
20 parts benzol. He mixed the ingredients that are usually 
employed in the manufacture of rubber, specifying 3 pounds 
of whiting, 1 pound barytes, 8 ounces lime, \y 2 pounds oxi- 
dized oil, and 8 ounces of india rubber. When these had been 
thoroughly mixed together and specially treated, alum was 
incorporated with them and well compounded, being passed 
through the mixing rollers cold. It was then calendered. 



ULTRA-VIOLET RAYS— OLIVIER 'S METHOD 61 

Raymond, in another English patent, uses for vulcanizing 
a mixture of benzine, camphor, chloride of sulphur, and oleic 
acid. 

VULCANIZATION BY ULTRA-VIOLET RAYS. 

Vulcanization by ultra-violet rays was brought to the 
attention of the rubber industry by Dr. Helbronner and Dr. 
Bernstein, at the International Rubber Conference at London 
in 1914. It is said that Victor Henri in 1909-1910 was the 
first to expose rubber to the ultra-violet rays, carrying out 
vulcanization with films of solution. French patent No. 460,780, 
issued July 26, 1913, international conventions, date July 26, 
1912, claimed the vulcanization of rubber solutions by ultra- 
violet rays and states that 3 per cent, plantation rubber and 
sulphur in benzine exposed in thin layers vulcanize rapidly, 
sulphur to the extent of from \ r / 2 to 2y 2 per cent, combining 
with the rubber. 

Crystalline sulphur, rather than flowers of sulphur or stick 
sulphur, should be used and the interesting suggestion is made 
that these solutions of rubber so vulcanized may have industrial 
application. They are said to be suitable for all kinds of cement- 
ing or rubberizing operations, and are capable of resisting all 
mechanical strains, as well as the action of heat. They can 
be used particularly for joining and rubberizing leather, and 
consequently will be valuable in the shoe industry. 

Also, the repairs of all rubber goods, tires, inner tubes, 
etc., can be readily carried out by means of vulcanized solu- 
tions. 

Two other patented methods of vulcanization by ultra- 
violet rays may be mentioned. 

olivier's method. 

The rubber solution, containing free sulphur, with or with- 
out certain organic or inorganic sulphides which are decom- 
posed by ultra-violet rays, such as carbon bisulphide, allyl sul- 
phide, or antimony sulphide, passes from a hopper on to an end- 
less steel band, which is carried by guide rollers round the greater 
part of the periphery of a mercury-vapor lamp. The lamp is 
surrounded by a double, hemicylindrical water-jacket of quartz, 



62 VULCANIZING PROCESSES 

in order to cut off heat rays. The time of exposure is quite 
short, in order to avoid the deleterious effect of prolonged ex- 
posure to ultra-violet radiation on the rubber. As an example, 
a layer of solution a fraction of a millimeter thick, at a dis- 
tance of 5 centimeters from the lamp, which is operated at 
220 volts and 3 amperes, requires an exposure of about 40 
seconds. After passing the lamp the solution is removed from 
the endless band to a receiving vessel by means of a scraper. 
bernstein's method. 

This consists in the exposure of rubber solution contain- 
ing sulphur, sulphide, or other vulcanizing agents to the action 
of ultra-violet rays under conditions to suit the circumstances, 
such as in vacuo, under heat and pressure, or in an atmosphere 
of neutral gas not containing oxygen. 

Helbronner and Bernstein consider vulcanization as a mere 
polymerization of the rubber under the action of a catalytic 
agent (sulphur). The sulphur becomes insoluble and unites 
with the india rubber. A certain action of the rubber is caused 
by the ultra-violet rays, and another by the sulphur, and the 
combined actions produce vulcanization. The sulphur becomes 
the catalyser under the action of the ultra-violet light. 

pressure cure. 

Pressure cure is the designation covering the several pat- 
ented methods of vulcanization by heat and sulphur, conducted 
either in air or an inert gas under pressure. It is one of the 
recent improvements in rubber shoe manufacture, displacing 
the ordinary steam-heated dry-air vulcanizing method, particu- 
larly for boots and heavy goods. The method originated in 
the United States. The chief advantage of pressure cure for 
rubber footwear seems to be greater solidity of the rubber com- 
position and more perfect contact of adjacent parts in the struc- 
ture of the goods due to expulsion of air by pressure. Essen- 
tially this result is also attained by subjecting the goods to 
vacuum or pressure treatment previous to the ordinary dry-heat 
curing without pressure. 

ELECTRIC VULCANIZATION. 

The substitution of electricity for steam is not new, but 
an improved method of vulcanizing rubber by electricity has 



VULCANIZING INGREDIENTS 63 

recently been patented that, according to the claims, not only 
effects a great saving in heat and labor, but insures a more 
uniform cure in less time. Metal contacting strips or plates 
are employed, through which is passed an electrical current, 
that is maintained for the proper length of time to effect a 
cure. By constructing the heating strip or plate at different 
points with sections of varying electrical resistance, the vul- 
canization of belting, packing, mats, tires and molded goods may 
be accomplished. 

SULPHUR BATH VULCANIZATION. 

Vulcanization by immersion in a bath of molten sulphur 
is adapted for the cure of pure rubber "dipped" articles or those 
made of cut sheet. It is conducted, at temperatures varying 
from 135 to 160 degrees Centigrade, in a specially constructed 
apparatus in which the melting of the sulphur is effected by a 
direct firing plant. The sulphur vapors are removed by a 
powerful exhauster. The vulcanized articles are freed from 
adhering sulphur by heating in soda solution. 

vulcanizing ingredients. 
Amorphous Sulphur. — The fusion of 1 pound of sulphur 
with 4 ounces of Canada balsam produces what is known as 
amorphous sulphur, which is said to cure rubber so that it will 
have no tendency to bloom. The preparation has a very pun- 
gent sulphurous odor. Patented by Dr. Wilhoft, of New York. 

Artificial Sulphuret of Lead.— There are several com- 
binations of lead and sulphur which may be produced arti- 
ficially. That one containing the most sulphur has a compo- 
sition of 13 per cent, of sulphur and 86 per cent, of lead. Its 
specific gravity is about 9.4. In color it is black. The other 
sulphur, compounds of lead have much less sulphur/ one con- 
taining but 9 per cent, and the other only 4 per cent. What 
is known as hyposulphite of lead is a mechanical mixture of 
the above first named, with a suitable percentage of sulphur to 
effect vulcanization. It is also known in the rubber trade as 
"Eureka compound," "burnt hypo;" and "black hypo." These 
compounds when pure — that is, when free from adulteration — 
are of great value. They produce goods that are jet black and 



64 VULCANIZING PROCESSES 

have little odor and are free from bloom. They are reckoned 
as the safest vulcanizing agents, as it is almost impossible to 
burn goods that depend upon their presence for cure. They are 
used in either dry or wet heats. 

Barium Sulphide is prepared from heavy spar by making 
a dough of it with charcoal and oil and subjecting it to a white 
heat. Sulphides of the alkaline metals, potassium, sodium, 
calcium, and barium, will vulcanize rubber, whence the term 
" alkalized rubber." 

Bromine. — A heavy deep red volatile liquid, possessing a 
most peculiar and unpleasant odor, and giving off vapors most 
irritating to the air passages and lungs. Its very name means 
stench. It has a powerful action upon most organic bodies, 
coloring animal matter brown, while it bleaches coloring mat- 
ters, dyes, etc. Its specific gravity is 3.18. A piece of sheet 
rubber dipped into bromine is vulcanized instantly. It is some- 
what soluble in alcohol, and very soluble in ether, bisulphide of 
carbon, chloroform, etc. Newbrough and Fagan filed two pat- 
ents in the United States for the use of bromine in vulcanization, 
both with and without iodine. By adding to iodine y 2 its weight 
of bromine, proto-bromide of iodine is formed, which is said 
to combine with india rubber and produce a hard compound 
on being exposed 1 hour to a temperature of 250 degrees F. 
To prevent the forming of an explosive the iodine and bromine 
were separately treated with oil of turpentine to which had 
been added a quarter of its weight of sulphuric acid. It was 
then mixed with the gum in the proportion of 2 pounds 11 
ounces to every pound of gum. Bromine was also used alone 
by these inventors, the material after molding being plunged 
into the liquid, and left there long enough to harden. To pre- 
vent the hardening of the material while in the bath, chloroform 
or any other solvent of rubber was added in the proportion of 
1 part to 9 parts of bromine; in other words, the rubber vul- 
canized in the air after its withdrawal from the liquid. 

Chlorine. — Chlorine is a greenish yellow gas at all ordi- 
nary temperatures. It has strong bleaching properties and also 
a very bad smell and action upon the respiratory passages. 
Under a pressure of 127 pounds to the square inch at 60 de- 



CHLORIDE OF SULPHUR— ANTIMONY 65 

grees F., chlorine condenses to a yellow liquid, having the 
specific gravity of 1.33. Chlorine cannot, as a rule, destroy 
mineral colors or blacks produced by carbon. Helm claimed 
that he was able to produce white hard rubber by incorporat- 
ing chlorine with the mass. 

Chloride of Sulphur. — Sulphur and chlorine form three 
compounds, the monochloride, the dichloride, and tetrachloride 
of sulphur. The substance commonly used in the arts is the 
first named or a mixture of the first two. It is an oily liquid 
of the specific gravity 1.7 and boiling at 239 degrees F. It 
has a pungent smell and decomposes on contact with water or 
watery vapor. Pure chloride of sulphur is of an orange yellow 
color of great density. It fumes strongly when exposed to the 
air, throws off the vapors of hydrochlorine, and is quite poison- 
ous, severely attacking the mucous membranes. It is widely 
known as the active agent in Parkes's cold-curing process, where 
it is used in connection with bisulphide of carbon. A common 
formula for this is chloride of sulphur, 1 part by weight, bi- 
sulphide of carbon, 30 to 40 parts by weight; immerse from 
60 to 80 seconds. In the manufacture of balloons and toy balls, 
the solution is a far weaker one. That for the outside dip is 
10 parts of chloride of sulphur to 100 parts bisulphide of carbon, 
while for the inside it is 16 parts chloride of sulphur to 100 
parts bisulphide of carbon. When it was common to cure 
proofed cloth by the cold process, it was done by wetting its 
surface with a mixture of 5 to 10 parts of chloride of sulphur, 
dissolved in 100 parts of bisulphide of carbon, then running the 
fabric over heated drums to evaporate the mixture. In the sul- 
phurization of oils for rubber substitutes chloride of sulphur 
plays a most important part, nearly all of the amber and white 
products being produced by its use. It also has a curious effect 
upon bastard gums, giving some of them temporarily the elas- 
ticity and appearance of high-grade rubber. 

Golden Sulphuret of Antimony. — This is prepared from 
black antimony by boiling it with caustic soda and sulphur for 
some time. The liquid is then clarified by filtration or settling 
and the clear part treated with a dilute acid, preferably muri- 
atic or sulphuric. A golden yellow precipitate is formed which 



66 VULCANIZING PROCESSES 

should be well washed in water, and dried at not too high a 
temperature in a darkish place. The results of this operation 
well carried out are constant and the composition should be: 
Antimony, 60.4; sulphur, 39.6. Golden sulphuret of antimony 
heated in a tube will give off sulphur which will deposit on 
the cool sides of the tube away from the flame and the residue 
will turn black, being indeed the black sulphide of antimony. 
All samples of this compound should be tested for free acid, 
by shaking up a little of the powder in a test tube with cold or 
hot water, and testing the water afterwards with some barium 
chloride and blue litmus paper. A white cloud in the first place 
and the reddening of the paper in the second place indicate the 
presence of more or less free sulphuric acid. Golden sulphuret 
prepared with muriatic acid will not respond to the first test, 
but will to the second. 

Golden sulphuret or antimony red (pentasulphide) is used 
more largely than any other form of antimony in rubber work. 
It is also called orange sulphide of antimony. 

Its composition is pentasulphide of antimony with calcium 
sulphate carrying free colloidal sulphur. The following typical 
analysis represents a standard American grade: 

Antimony, as pentasulphide 30 .00 

Calcium sulphate 43.00 

Free sulphur 17 . 00 

Water of crystallization 9.00 

Moisture 1.00 

The calcium sulphate and water of crystallization are pres- 
ent as legitimate constituents and are in no sense adulterants. 

Golden antimony may be made with various percentages 
of free' sulphur, although the usual standard is 17 per cent, for 
rubber work. As ordinarily used this allows ample sulphur for 
vulcanization. 

Properly used, this ingredient produces some of the best 
effects found in vulcanized rubber, in color, texture, and dura- 
bility. It should never be mixed on a very hot mill, should be 
sheeted and placed in cooling racks if it is not to go right to 
the calender, and should be cured in as low a heat as possible. 
The ideal result will be of a golden yellow color, with a very 
slight bloom, if any. It is used only in high cost goods. 



HONEYCOMB SULPHUR— LIVER OF SULPHUR 67 

In rubber compounding golden antimony serves several im- 
portant purposes. It is valuable as a pigment but, aside from 
this, its function is chiefly chemical, since it furnishes sulphur 
in colloidal form for curing. This is ideal for vulcanization, 
because the rubber can be fully cured without containing an 
excess of sulphur to cause unsightly blooming and subsequent 
deterioration by aging. The use of antimony also results in 
producing tough stock of increased tensile strength over pure 
rubber and sulphur as found, for example, in automobile tubes 
and rubber bands. 

Honeycomb Sulphur. — A vulcanizing compound made by 
boiling a pound of sulphur and two ounces of benzoin gum 
together, 1 pound of this material being mixed with a quart of 
boiled linseed oil. 

Hyposulphite of Lead. — See Artificial Sulphuret of Lead. 

Iodine is manufactured from seaweed and is a black-gray 
substance occurring in small shining scales. Its specific grav- 
ity is 4.94 and it fuses at 239 degrees F., giving off violet 
vapors. It is readily soluble in alcohol, benzol, chloroform, and 
sulphide of carbon. In addition to the formula given under 
the head of bromine, Newbrough and Fagan patented the com- 
bination of iodine and sulphur. In this the sulphur was boiled 
in turpentine, and the oil decomposed and deposited with the 
sulphur at the bottom of the vessel was used in the operation, 
after being washed in dilute sulphuric acid and dried. The iodine 
was treated in the same manner to prevent explosions. Equal 
parts of each were melted together and incorporated in the 
proportion of 2 ounces 5 drams to 1 pound of rubber. After 
shaping, the articles were put in a vulcanizer and during the 
first fifteen minutes exposed to a dry heat, gradually increas- 
ing to 320 degrees F., remaining there 5 minutes, then drop- 
ping rapidly to 250 degrees F., and continuing for an hour at 
that temperature. 

Liver of Sulphur. — This is really pentasulphide of potas- 
sium, and is obtained by mixing carbonate of potassium to- 
gether with sulphur. It is called liver of sulphur on account 
of its brown color. As it is quite volatile it should be kept in 



68 VULCANIZING PROCESSES 

well closed glass vessels. The fluid for vulcanizing purposes 
is a concentrated solution of the pentasulphide, about 25 de- 
grees Baume being right for use. To cure with it the liquid 
is brought to the boiling point in a porcelain vessel, the articles 
to be vulcanized being immersed in it. This is known as 
Gerard's process and is said to be inexpensive and perfectly safe. 

Milk of Sulphur. — In America this material and pre- 
cipitated sulphur are identical and officially 99.5 per cent. pure. 
In Great Britain, milk of sulphur contains approximately 50 
per cent, of calcium sulphate, while precipitated sulphur is of- 
ficially 99.5 per cent, pure and is the form utilized in rubber 
work. 

Nantusi is a vulcanizing agent and preservative for rub- 
ber, consisting of sulphur and paraffin, and in use in England. 
It is offered as preventing the superficial cracking of rubber 
exposed to the atmosphere ; preserving the quality of the rubber ; 
doing away with the possibility of acidification in sulphur as 
ordinarily used; and reducing the cost of the mixing. It is 
said to be a special mixture of paraffin and sulphur. 

Pentasulphide of Antimony. — The chemical name for 
golden sulphuret of antimony (which see). 

Proto-Chloride of Sulphur. — See Chloride of Sulphur. 

Sulphide of Lead. — Occurs native as galena and is one of 
the ores of lead, having a specific gravity of 7.2 to 7.7. Com- 
mercially it is a black powder, of specific gravity 6.9. Its com- 
position is 86.6 per cent, of lead and 36.4 per cent, of sulphur. 
Sulphide of lead is a very useful black pigment, and one that 
is used quite largely in rubber works, as it is a good filler and 
assists in vulcanization. It is often made from pure white lead 
by very simple treatment. It materially assists the resiliency 
of Para compounds. 

Sulphur Lotum. — A name for sublimed sulphur that has 
been washed to remove sulphurous acids, and carefully dried. 

Sulphide of Zinc. — Sulphur forms with zinc two sul- 
phides. One of these, the monosulphide, corresponds to zinc 



SULPHUR— VESUVIAN WHITE 69 

blende, which, as found native, is of various colors, from yel- 
low to black. Its specific gravity is from 3.5 to 4.2. The other 
is a pentasulphide artificially prepared and occurs in the form 
of a white powder. Upon ignition in the absence of air this 
latter substance loses four-fifths of its sulphur but the tempera- 
ture at which this takes place is too high to render it available 
as a source of sulphur of vulcanization in compounding rubber 
mixtures. With a slight addition of sulphur it is used in the 
production of white goods. 

Sulphur occurs in a number of different forms, and under 
various names as brimstone, flowers or flour of sulphur, roll 
sulphur, rock sulphur, etc. Its specific gravity is 1.98 to 2.06. 
It melts at 239 degrees F., thickens and becomes orange yellow 
at 320 degrees F. ; at 428 degrees it is semi-solid and red, and 
on carrying the heat higher it becomes browner and boils at 
788 degrees F. Some of the sulphur now used commercially is 
recovered from alkali waste; formerly most of it came from 
Sicily, where it is found native. The American supply now 
comes largely from Louisiana, where, by the injection of steam 
to deep-lying deposits, the sulphur is melted and forced to the 
surface. It is more generally used in rubber works than any 
other ingredient, and in all proportions from 3 per cent, up to 
100 per cent, of the weight of the rubber. The ordinary form 
in which it is found in the rubber factory is in a yellow powder, 
known as flowers of sulphur. It has a slight affinity for mois- 
ture, and careful manufacturers keep it covered from air to 
avoid the formation of sulphurous or sulphuric acids. Com- 
bined with certain oils by heat, it forms the black sulphur sub- 
stitutes that are often used in rubber compounding. Sulphur 
in the form of rolled brimstone is pulverized, sifted and used 
in the place of flowers of sulphur, in France, and is equally 
good and cheaper. 

Sulphur Balsam. — A solution of sulphur in fixed oils, 
consisting of 2 ounces of flowers of sulphur in 8 ounces of 
linseed oil, used in proofing compounds. 

Vesuvian White. — A special vulcanizing material manu- 
factured in England, for use in the manufacture of tennis balls 
and other goods. 



70 



VULCANIZING PROCESSES 



Vulcanine. — An English vulcanizing preparation, used for 
both steam and dry heat goods. It occurs either as a white or 
a black powder, depending upon the line of goods on which it 
is to be used. 

Vulcole. — A paste furnished in two colors, white and 
black, added to certain compounds, prevents blooming. It also 
has the quality of rendering flowers of sulphur inert if used 
in excess, so that 50 to 75 per cent, can be used in an ordinary- 
soft compound. 

The table following indicates vulcanizing pressure in pounds 
per square inch in gage, and corresponding temperatures by the 
Fahrenheit scale: 

VULCANIZING PRESSURES AND TEMPERATURES. 



Pressure 
in lbs. 
per sq. 
inch in 
gage. 



Tempera- 
ture in 
Fahren- 
heit 
degrees. 



7 232.3 

8 234.7 

g 237.1 

10 239.4 

11 241.6 

12 243.7 

13 245.8 

14 247.8 

15 249.7 

16 251.6 

17 253.5 

18 255.3 

19 257.0 

20 258.7 

21 260.4 

22 262.0 

23 263.6 

24 265.2 

25 266.7 

26 268.2 

27 269.7 

28 271.1 

29 272.6 

30 273.9 

31 275.3 

32 276.7 

33 278.0 

34 279.3 

35 280.5 

36 281.8 

37 283.0 

38 284.2 



Pressure 
in lbs. 
per sq. 
inch in 
gage. 



Tempera- 
ture in 
Fahren- 
heit 
degrees. 



39 285.4 

40 286.6 

41 287.8 

42 288.9 

43 290.1 

44 291.2 

45 292.3 

46 293.4 

47 294.4 

48 295.5 

49 296.5 

50 297.5 

51 298.6 

52 299.6 

53 300.6 

54 301.5 

55 302.5 

56 303.5 

57 304.4 

58 305.3 

59 306.3 

60 307.2 

61 308.1 

62 309.0 

63 309.9 

64 310.8 

65 311.6 

66 312.5 

67 313.3 

68 314.2 

69 315.0 

70 315.8 



Pressure 
in lbs. 
per sq. 
inch in 



Tempera- 
ture in 
Fahren- 
heit 
degrees. 



71 316.7 

72 317.5 

73 318.3 

74 319.1 

75 319.9 

76 320.7 

77 321.4 

78 322.2 

79 323.0 

80 323.8 

81 324.5 

82 325.2 

83 326.0 

84 326.7 

85 327.4 

86 328.1 

87 328.9 

88 329.6 

89 330.3 

90 331.0 

91 331.7 

92 332.3 

93 333.0 

94 333.7 

95 334.4 

96 335.1 

97 335.7 

98 336.4 

99 337.0 

100 337.7 



PLANTATION HEVEA AND OPTIMUM CURE 71 

PLANTATION HEVEA AND THE OPTIMUM CURE. ( 

The reliability of fine hard Para from wild Amazonian 
sources serves as a standard for the preparation of plantation 
fine as they are both derived from Hevea brasiliensis. A great 
deal of scientific research has been devoted to seeking the causes 
of variation in the time required to vulcanize smoked and un- 
smoked plantation fine to the optimum cure, by which is meant 
the best physical results attainable from a given specimen of 
rubber. 

Exhaustive investigations in this field have been carried 
on continuously for several years in the chemical laboratory and 
experimental vulcanizing factory of the Department of Agri- 
culture, Federated Malay States, by B. J. Eaton and J. Grantham. 
The details of this study have been published at intervals in the 
"Journal of the Society of Chemical Industry," London. It is 
sufficient here to indicate the results by brief abstracts and quo- 
tation of summaries as given by the authors. 

There is a marked tendency to look to fine hard Para as 
the standard because manufacturers have had experience with 
it extending over many years. That, however, is the only argu- 
ment in its favor. The term uniformity, as applied to rubber, 
means rubber of the same type. Different types of rubber may 
vary in mechanical strength, but variation in vulcanizing quality 
is far more important to the rubber manufacturer. The matter 
of form and appearance is of 'little consequence to the manu- 
facturer, although important to the broker, buying and selling 
on looks rather than by test. 

In vulcanizing rubber with sulphur the manufacturer has 
recourse to three methods in securing a given result. He may 
vary the amount of sulphur, or the temperature and time of 
vulcanization. In the experimental work of the agricultural 
department, the sulphur and temperature were fixed and the 
time varied. In the original experiments all the rubbers tested 
gave their best results in 2y 2 to 2}i hours. Different mechanical 
results were obtained by changing the time of cure. 

Rubber consists approximately of 94 per cent, of caout- 
chouc, 1 per cent, of mineral salts, 2 to 3 per cent, of resins, 
and 2 to 3 per cent, of protein. The ingredient most liable to 



72 VULCANIZING PROCESSES 

change is the protein, and probably some substance derived 
from this acts as an accelerator. Experimentally it was found 
that this change occurs in the coagulum if left for six days 
before being creped. No evidence of this change can be de- 
tected in the appearance of the rubber, which in consequence 
requires to be tested to ascertain its vulcanizing quality. 

As concerns rubber estate practice several factors affect 
vulcanization. These are thickness, i. e., amount of serum re- 
moved; smoking, which retards vulcanization; the use of 
formalin or other preservatives; amount of acetic acid used in 
coagulation, and the dilution of the latex. The age of the tree 
also affects the proportion of protein and other constituents of 
the latex. 

The more uniform methods now adopted on many estates 
tend to greater uniformity of product; but variability is due 
chiefly to the difference in rubber from different estates. 

In these experiments, in preparing the block of pan coagu- 
lum, which was left in this form for some days, a really new 
type of rubber has been discovered. It vulcanizes more rapidly 
than fine hard Para and ordinary plantation grades, which take 
medium time. Only eight or nine samples of fine hard Para 
have been tested so far, but it is remarkable that all vulcanized 
in about the same time. 

It is, therefore, natural for the small manufacturer to rely 
on fine hard Para. The reason for its lack of variation is at- 
tributable to the uniform method of its preparation, and not 
because of any intrinsic value of the method. As it may require 
two or three months to prepare a ball of fine hard Para, any 
variations in its quality are averaged. 

The formation of the accelerating substance is believed to 
be effected by bacteriological action. Rapid-curing samples 
show better mechanical tests than those that cure slowly. 

Rapid vulcanization eliminates the danger of overheating, 
and that is probably the reason for the increase of strength. 

Dr. Schidrowitz first pointed out this variability in rate 
of cure in plantation rubber, of which the experiments at the 
agricultural department first showed the cause. It is possible 



VARIABILITY IN RATE OF CURE 73 

now to prepare a rubber which will vulcanize correctly at any 
particular time, within certain limits. 

Subsequent experiments have been directed to ascertaining 
the nature of this accelerating substance and its behavior under 
different treatments, to determine its probable constitution. 
These efforts have resulted in the isolation or preparation of a 
substance or substances from the latex serum to which accelera- 
tion in rate of cure can be attributed, and evidence has been 
obtained of the presence of a second substance which also has 
a similar effect. 

The experimental results confirm the theory that the rate 
of cure is influenced by the amount of an accelerating agent 
formed by the decomposition of some constituent of the latex, 
and that this substance is a decomposition product of the 
protein or nitrogenous constituents of the latex, produced 
usually in the freshly coagulated raw rubber by the action of 
micro-organisms, which gain access to the latex after it leaves 
the tree, or possibly in some cases decomposition by chemical 
action. The retarding effect of smoking, on the rate of cure, 
has proved to be a more complicated problem than at first ap- 
peared. The retarding effect, though invariably shown by slab, 
has been found not to be constant in sheet, especially in thin 
sheet. This is due to the fact that, in smoking rubber, more than 
one variable factor, influencing the rate of cure, is present. 

In most of their experiments the authors, Eaton and Grant- 
ham, used raw rubber in the form of slab slightly pressed, or 
unpressed coagulum containing a large percentage of serum. 
The latex was coagulated one day about noon, left in the serum 
till about 10 A. M. the following day and then rolled under a 
wooden rolling pin on a sloping table. All samples were even- 
tually converted to thin crepe before vulcanizing. 

CAUSES OF VARIABILITY IN RATE OF CURE. 
The investigation is in three divisions : 

PART I. EXPERIMENTAL. 

Part I embraces a group of experiments for determining — 
The time necessary to develop the change in slab rubber, 
causing an increase in rapidity of cure. 



74 VULCANIZING PROCESSES 

The effect of antiseptics, heat and cold. 

The effect of formalin. 

The effect of soaking in running water. 

CONCLUSIONS UNDER PART I. 

1. That the rate of vulcanization of rubber from any given 
latex is determined by the extent to which a certain change 
takes place subsequent to coagulation. 

2. This change is normally limited to the first few days 
after coagulation. The change is progressive and reaches a 
maximum in "slab" rubber (i. e., coagulum containing a large 
proportion of the serum) in approximately six days after co- 
agulation. 

3. The change can be arrested either partially or com- 
pletely by the action of formalin, heat, and cold. It is also 
arrested by creping shortly after coagulation, which may be 
due either to the larger surface exposed or to the more rapid 
drying, or both, combined with the removal of most of the 
serum in machining to crepe form. 

4. The complete arrest or inhibition of the change by 
formalin (similar effects have been obtained with other anti- 
septics) and by the action of both heat and cold, indicates the 
formation by biological action of a substance which increases 
the rate of cure of raw rubber, the decomposition being prob- 
ably of an anaerobic nature. There is no evidence that the 
change is due to chemical agencies. 

In this connection experiments carried out on latex frozen 
for several days at 12 to 15 degrees F., are of considerable 
interest, since by freezing for this period, the rubber no longer 
cures rapidly, even if left for a considerable period afterwards 
at 84 degrees F. 

[The method of freezing latex to produce rubber has been 
patented in the Federated Malay States. Latex after freezing 
for 4 to 5 hours is coagulated and, on thawing the solid block 
thus formed, a solid coagulum is formed, whereas latex can be 
frozen for a short period and on thawing is reconverted into 
latex.] 



VARIABILITY IN RATE OF CURE 75 

PART II. EXPERIMENTAL. 

Part II deals with the probable nature of the constituent 
of the latex involved in the changes in raw rubber, and the 
nature of the constituents which are responsible for the vari- 
ations in rate of cure of different rubbers. 

The experiments of Part II included the addition of pro- 
teins to rubber and the effect was determined of the following 
additions : 

Casein and peptone. 

Decomposed casein. 

Protein from the latex. 

Evaporated serum minus protein. 

Decomposed protein from serum. 

CONCLUSIONS UNDER PART II. 

There exist in serum two substances : ( 1 ) a substance of 
the nature of protein, precipitated or coagulated by heat, which 
is ineffective in accelerating the rate of vulcanization unless 
decomposed; (2) a soluble substance, only obtained by evapo- 
ration and not easily decomposed, which has itself an accelerat- 
ing action on vulcanization. 

Decomposed precipitated protein is effective in much smaller 
quantity than serum residue obtained by evaporation, after the 
heat coagulated protein has been removed. 

In the ordinary preparation of sheet and crepe rubbers the 
greater part of the serum is removed in machining the coagu- 
lum, and the whole of the soluble products may be washed out 
in creping, so that normally the accelerating effect of the soluble 
serum is nothing. All of the experiments of the first part show 
the gradual development of the accelerating substance during 
the first few days after coagulation. This is attributed to. the 
decomposition of protein (similar in nature to that precipitated 
from the serum by heat), which is precipitated with the rubber 
during coagulation. 

PART III. — ANALYTICAL. NITROGEN CONTENT OF RUBBER AND THE 
RATE OF VULCANIZATION. 

The contrast between the high nitrogen content of a slow- 
curing crepe, compared with the low nitrogen content of fast- 
curing crepe from a slab rubber, can only be explained on the 



76 



VULCANIZING PROCESSES 



theory that, in the slab rubber, decomposition of the protein 
or nitrogenous substance takes place. A soluble portion is 
washed out during creping, and the insoluble residue, or part 
of it, is presumably the substance causing acceleration in rate 
of cure in the case of slab rubbers. 

In view of the vulcanizing results obtained in Parts I and 
II, the authors have analyzed a large number of their samples 
which are tabulated below, together with the rate of cure de- 
termined by the load-stretch curve method. 



Per Cent Opti- 

oi mum 

Nitrogen Time of 

in Dry Cure in 

Sample. Hours. 

0.31 254 

0.26 VA 

0.19 154 

0.16 154 

0.17 154 

0.17 VA 

0.18 VA 

0.18 VA 

0.33 2^ 

0.30 VA 

0.16 1J4 

0.11 1J4 

0.13 VA 

0.12 VA 

0.12 154 

0.18 154 

0.17 154 



Per Cent Opti- 

of mum 

Nitrogen Time of 

in Dry Cure in 

Sample. Hours. 

0.42 2^4 

0.19 154 

0.37 254 

0.36 254 

0.36 ZVt. 

0.35 254 

0.38 3V 2 

0.20 154 

0.20 154 

0.40 254 

0.19 1 

0.40 354 

0.33 3 

0.23 254 

0.27 2% 

0.36 254 



Per Cent Opti- 

of mum 

Nitrogen Time of 

in Dry Cure in 

Sample. Hours. 

0.28 254 

0.22 154 

0.31 254 

0.19 154 

0.24 154 

0.37 354 

0.24 1 

0.38 354 

0.20 1 

0.39 354 

0.26 1 

0.36 354 

0.27 154 

0.38 354 

0.40 354 

0.19 254 



In every case, the amount of nitrogen in a slow-curing 
rubber, is about 50 to 100 per cent, greater than the amount of 
nitrogen contained in a fast-curing slab rubber, the amount of 
nitrogen being determined on all samples after conversion to 
crepe and drying. 

On the other hand, the amount of nitrogen in samples of 
rubber prepared by the evaporation of thin layers of latex, or 
by pouring out the latex into thin layers, after addition of acid 
coagulant, and allowing the thin sheets thus obtained to dry 
rapidly, is high, and amounts in some cases to 0.5 per cent. 
Such samples are rapid-curing, although the percentage of nitro- 
gen indicates that no decomposition of the protein or nitrogen- 
ous constituents of the rubber has taken place, the factor de- 



VARIABILITY IN RATE OF CURE 77 

ciding rapidity of cure being apparently, in this case, the unknown 
substance present in the evaporated serum after removal of the 
major portion of the protein. 

SUMMARY. 

1. The experiments and results of Part I show that one 
factor which causes variability in respect of rate of cure in 
plantation Para rubber is produced during the first six days 
after coagulation and that the change which takes place in the 
coagulum is progressive during this period, while after this 
period, no further change, under ordinary conditions, takes 
place. 

2. The action of antiseptics, such as formalin, as well as 
heat and cold, are also shown to inhibit this change, while soak- 
ing of the fresh coagulum in running water considerably retards 
the rate of cure. 

3. The action of formalin is also shown to be partly, 
though not to any great extent, an action on the accelerating 
agent after its formation. 

4. Experiments on the cold storage of freshly coagulated 
rubber show that while the change which produces rapidity of 
cure is inhibited as long as the coagulum remains in cold stor- 
age, if the rubber is removed again and allowed to remain, 
without machining, for a further period (13 days or possibly 
less) at ordinary atmospheric temperatures (about 85 degrees F. 
in the Federated Malay States), rapidity of cure is again brought 
about. 

5. All the experiments of Part I suggest that the change 
which produces rapidity of cure in the rubber is caused by 
biological agencies, that is to say, micro-organisms entering the 
latex after collection and remaining in the coagulum, and that 
the change is probably a decomposition of the protein or nitro- 
genous substances present in the coagulum, producing an ac- 
celerating agent which is a decomposition product of the 
proteins. 

6. The experiments of Part II, on the slow-curing rub- 
bers of various proteins and nitrogenous substances, and their 
decomposition products, including the proteins from the latex 
serum decomposed by suitable methods after separation from 



78 VULCANIZING PROCESSES 

the serum, confirm the conclusions from the experimental evi- 
dence contained in Part I, and show that the original proteins 
have little or no effect under the conditions employed, while 
the decomposed proteins have a marked effect. 

7. Experiments with undecomposed evaporated serum, 
after separation of the proteins coagulated by heat, suggest the 
presence of a second factor which accelerates the rate of cure, 
and is due to some substance originally present in the latex. 

8. In the case of the author's so-called "slab" rubbers, 
possibly both factors are responsible for the acceleration of the 
rate of cure, and it would appear that the second factor may 
be responsible for the actual superior tensile properties of the 
rubber. Some evidence to this effect is contained in the com- 
paratively poor quality of the rubbers to which the protein 
decomposition product has been added, in which the second fac- 
tor has been removed, and also in the good quality in the case 
of the evaporated latex samples and the rubber to which the 
evaporated serum has been added. Further experiments are, 
however, necessary to confirm this. 

9. Experiments with evaporated latex, which contains all 
the serum constituents and is dried with sufficient rapidity to 
prevent decomposition of the proteins, also confirm the presence 
of this second factor. 

10. The nitrogen figures given in Part III still further 
confirm the decomposition theory, that is to say, the production 
of some substance from the protein which accelerates the rate 
of cure, the nitrogenous portion which becomes soluble in water 
and is removed on creping being non-essential. The high nitro- 
gen content, on the other hand, in rapidly curing rubbers pro- 
duced by evaporation of the latex, without decomposition of 
the protein, again confirms the evidence obtained as to a second 
factor which is probably of a non-nitrogenous nature. 

11. These experiments and results also show why it has 
not been possible hitherto to connect the nitrogen content of a 
rubber with its rate of cure, since a rapidly curing rubber may 
have either a low or high nitrogen content, and indicate how 
previous workers have gone astray, or not gone sufficiently far 



VARIABILITY IN RATE OF CURE 79 

in their investigations, in connection with the protein or nitro- 
genous constituents of latex and rubber. 

12. Many other experiments on nearly 1,000 samples of 
rubber all confirm the above results and conclusions. 

13. A further investigation is now being made as to the 
exact nature of the protein decomposition product, which ac- 
celerates the rate of cure, and as to the nature of the second 
factor responsible for acceleration, together with the numerous 
subsidiary factors which influence the rate of cure, a number 
of which have already been investigated. 

The authors have since found that the protein left in sheets 
of average thickness can be decomposed and so produce a more 
rapidly curing sheet rubber by simply rolling up the sheets after 
machining in order to retain sufficient moisture content for the 
bacterial decomposition. This demonstrates that the rapidity of 
cure of the so-called slab rubber is largely due to the decompo- 
sition of protein nominally retained by the rubber, even after 
rolling to sheet form. These results also show the importance 
of the rate of drying during early stages, as a factor in the 
preparation of sheet rubber, in order to have a uniform rate 
of cure. 

Dr. Henry P. Stevens, of London, in conjunction with the 
late Dr. Clayton Beadle in 1912 first published his work on the 
rate of vulcanization of plantation rubber. He was the first to 
show that the nitrogenous or so-called insoluble constituents of 
rubber affect the rate of cure, and that they could be to some 
extent replaced by the addition of peptone, casein, etc. Later 
Stevens showed that the increased rate of cure was due to the 
formation of nitrogenous bases, probably formed by the putre- 
factive changes which set in when the unwashed coagulated 
latex was allowed to stand. He separated these bases as phospho- 
tunstates and proved their efficiency as vulcanizing accelerators 
by adding them to ordinary crepe rubber and showing the in- 
crease in rate of cure produced. 



CHAPTER V. 

ORGANIC AND INORGANIC ACCELERATORS. 

The following summary represents an effort to classify the 
principal nitrogen-bearing accelerators in a logical manner, and 
to record concisely their characteristics and efficacy as described 
by R. Ditmar and translated into French for "Le Caoutchouc et 
la Gutta-Percha," by Georges Noyer; Andrew H. King in 
" Metallurgical and Chemical Engineering " ; S. J. Peachey and 
Douglas F. Twiss in " The India Rubber Journal" ; and others. 

Whatever may be the future of synthetic rubber, the in- 
vestigations in connection with it led to the discovery of organic 
accelerators which have revolutionized several lines of rubber 
manufacture. It was found that synthetic rubber could not be 
vulcanized without the presence of certain organic catalyzers to 
facilitate the union of rubber and rubber-like substances with 
sulphur, and when all natural rubber was substituted the in- 
creased rapidity of vulcanization was truly remarkable. The 
difficulty, as for a time with plantation rubbers, appears to have 
been the absence of certain so-called impurities found evenly 
distributed throughout Para rubber coagulated by the Amazon 
method. These natural catalyzers of rubber latex are believed 
to be decomposition products and related to the proteins. It is 
certain that all organic accelerators yet known are nitrogen- 
bearing and many have amino groups, so that the function of 
nitrogen appears to be important. 

Manufacturers who had been * using the old, well-known 
mineral accelerators began to experiment with these new or- 
ganic catalyzers and found that they could double their output 
without expensive increase of steam pressure or danger of im- 
pairing the product by high temperature. Those engaged in the 
production of cheap molded goods discovered that by employing 
both high temperatures and catalyzers their increased output 
would take care of overhead. 

While this most important recent development in rubber 
chemistry is still in its infancy, there is already considerable 

80 



ORGANIC ACCELERATORS 



81 



generalization and a goodly amount of definite facts on which 
to build. It is thought that, unlike the mineral accelerators 
which undergo no chemical change during vulcanization, an 
organic catalyzer unites with one of the reacting substances and 
forms an unstable compound which then reacts with the other 
substance. Meanwhile the catalyzer is set free and the entire 
process is repeated. From a mechanical standpoint a catalyzer 
is most conveniently mixed with a solid capable of being very 
finely pulverized. A high boiling point is essential to prevent 
vaporizing during vulcanization and consequent spongy appear- 
ance, known as " blowing." 

The most important organic accelerators are as follows: 



Aniline oil. 

Carbon bisulphide addition products 
with : 
Aniline. 
Dipenylthiourea or thiocarbanil- 

ide. 
Dimethylaniline. 
Tetrahydropyrrole. 
Dimethylamine. 

/3£ Dimethyl x methyl trimethy- 
lene amine. 
Ammonium compounds : 
Ammonium borate. 
Aldehyde ammonia. 
Quaternary ammonium bases. 
Amino compounds : 

Accelerene or paranitroso dime- 
thylaniline. 
Para-phenylenediamine. 
Tetramethylenediamine. 
Hexamethylene-tetramine or hex- 
amethyleneamine or formin. 



Sodium amide. 

Naphthylenediamine. 

£/3 Dimethyl A trimethyleneamine. 

Trimethyleneamine. 

Benzylamine. 

Nitroso dimethylaniline. 
Piperidine and derivatives : 

Piperidine or aminopentane. 

Methyl piperidine. 
Quinoline derivatives : 

Quinoline sulphate or quinoline 
sulphonic acid. 

Quinosol. 

Oxiquinoline sulphide. 
Miscellaneous : 

Anthraquinone. 

Antipyrine. 

Naphthylamine. 

Urea derivatives. 

Anilides. 
Formanilide. 
Thioformanilide. 



Several of these accelerators are covered by patents and 
must be purchased through certain dealers who are prepared to 
quote to the consumer prices inclusive of the license fee of the 
patent owners. 

The catalyzers in question are piperidine and methyl pip- 
eridine, tetramethylenediamine, hexamethylene-tetramine, thio- 
carbanilide, and aniline hydrochloride. The first three of these 
are not made in the United States at present. 

ANILINE. 

Aniline. — This material, described in Chapter XI, has been 
extensively employed as an accelerator in rubber work for a 



82 ORGANIC AND INORGANIC ACCELERATORS 

number of years, particularly in the manufacture of automobile 
tires and tubes. 

To obviate the poisonous effects of aniline it is essential 
to protect the workmen by the use of waterproof outer gar- 
ments, such as rubber shoes, gloves and aprons to prevent the 
absorption of the liquid by contact with the skin. In addition 
it is also necessary to remove thoroughly and rapidly all aniline 
fumes arising from the warm rubber during the milling and 
calendering and generally by ventilation to provide an abundance 
of fresh air in the work rooms. 

CARBON BISULPHIDE ADDITION PRODUCTS. 

With Aniline. — Diphenylthiourea, or thiocarbanilide, is one 
of the earliest known organic accelerators. It takes the form 
cf large colorless tablets melting at 154 degrees C, and is a 
very efficient catalyzer, particularly for quick-curing stocks, be- 
cause it does its work at the very beginning of vulcanization. 
The proportions used vary from x / 2 to 3 per cent. 

With Dimethylaniline. — Cited by Ditmar and King. 

With Tetrahydropyrrole. — Known as pyrrolidin in Germany. 
Cited by Ditmar and King. 

With Dimethylamine. — This substance gives an active addi- 
tion product. With Para, 100 per cent, sulphur and the addi- 
tion of 1 per cent, of the compound of carbon bisulphide and 
dimethylamine vulcanization takes place completely with 15 
minutes' cure at 135 degrees C. (German patent 269,512.) 

With )3j3 Dimethyl x methyl Trimenthylene Amine. — Cited 
by Ditmar. 

AMMONIUM COMPOUNDS. 

Ammonium Borate. — This noticeably effects the cure, but 
the fact has only scientific interest, according to Ditmar. 

Aldehyde Ammonia. — This very satisfactory catalyzer is 
readily soluble in water, sparingly soluble in alcohol, and almost 
insoluble in ether. It melts between 70 and 80 degrees C. and 
sublimes without decomposition at 100 degrees C. Its efficacy 
as an accelerator, according to King, may be seen in the fact 
that 100 parts Para, 10 parts sulphur, and 1 part aldehyde 
ammonia will cure in 30 minutes at 45 pounds steam pressure, 
140 degrees C. (Ditmar says 1 hour at 3 atmospheres — 42 



ORGANIC ACCELERATORS S3 

pounds — while without the accelerator 2 hours would be re- 
quired), whereas 90 parts Para, 9 parts sulphur, and 1 part 
lime require 85 minutes at the same pressure for a cure. 

Quaternary Ammonium Bases. — These are covered by Bayer 
& Co.'s patents of 1914, together with aldehyde ammonia, 
para-phenylenediamine, sodium amide, benzylamine, and naph- 
thylenediamine, all rapid accelerators. 

AMINO COMPOUNDS. 

Accelerene. — This widely used English catalyzer is among 
the most powerful known accelerators. When used in the pro- 
portion of H to K of 1 per cent, it reduces the required 
period of vulcanization to one-third normal with highly satis- 
factory results; and in conjunction with certain other familiar 
substances in quick repair compounds reduces the period of 
cure to one-eighth normal. Cheap mixings containing consider- 
able reclaim or waste, particularly if golden antimony sulphide 
be present but no free sulphur, do not respond so readily as 
medium and high-class mixings. In such cases sufficient free 
sulphur must be added and the proportion of antimony sul- 
phide may be reduced to that needed to give the desired color, 
after which the usual acceleration will be attained. In the manu- 
facture of vulcanite the addition of 24 of 1 per cent, of accelerene 
to a mixture consisting of 100 parts rubber and 40 parts sulphur 
reduced the period of vulcanization from 6 to 2 hours, yield- 
ing a hard and very durable product. 

Essentially paranitroso dimethylaniline, and wholly differ- 
ent from the German type of accelerators, accelerene owes its 
activity to the presence of the nitroso group, and not to feeble 
basic properties. Aside from its high acceleration it possesses 
several characteristics in use that are of great value. Goods 
vulcanized in its presence show somewhat greater tensile strength, 
probably due to the diminished degree of depolymerization pos- 
sible in so short a period of heating. Vulcanization stops when 
the goods are taken from the pan or press, so they suffer little 
deterioration in storage, tests demonstrating this now covering 
a period of two years. Sulphuring-up may also be entirely 
prevented by its use, though at the sacrifice of acceleration. 
The quantity of sulphur may be reduced to 3 or 3^ per cent. ; 



84 ORGANIC AND INORGANIC ACCELERATORS 

}£ per cent, of accelerene is then added and the mixing cured 
in the ordinary manner. As employed for this purpose the 
catalyzer facilitates a complete combination of rubber and sul- 
phur, with the result that little or none of the latter remains 
in the rubber. 

Para-phenylenediamine. — This very poisonous catalyzer 
melts at 140 degrees C, sublimes without decomposition at 
267 degrees C, . is readily soluble in alcohol and ether, and 
moderately so in water. In Bayer & Co.'s German patent No. 
280,198, January 1, 1914, it is stated that this accelerator gives 
good satisfaction with synthetic rubber, 100 parts isoprene 
rubber having been cured completely upon being mixed with 
10 parts sulphur, 2 parts para-phenylenediamine and being 
heated in a press for 15 minutes, at 45 pounds steam pressure. 

Tetramethylenediamine. — Known also as putrescine, this is 
a natural product of protein decomposition formed during the 
putrefaction of animal matter such as fish. It is produced 
chemically by Bayer & Co. 

H examethylene-tetramine . — Known also as Hexamethy- 
leneamine and Formin. This accelerator is largely used. It 
comes as a fine white crystalline powder. The U. S. P. grade 
is free of moisture while the so-called technical grade usually 
contains about two and one-half per cent, of water. 

It is very soluble in water and as it vaporizes freely in 
the operations of mixing and calendering it occasions consider- 
able trouble in the form of a rash or eruption on the skin, 
particularly on exposed surfaces moistened with perspiration. 
The use of gloves, and otherwise protecting exposed portions 
of the body, minimizes the annoyance. 

Miscellaneous Amines. — Other amino compounds cited by 
King as of lesser importance yet having some accelerating 
power include: sodium amide (rapid acceleration according to 
Ditmar) ; naphthylenediamine (rapid acceleration according to 
Ditmar) ; trimethyleneamine, benzylamine (rapid acceleration 
according to Ditmar) ; /8/s dimethyl A trimethyleneamine, and 
nitroso dimethylaniline. 

PIPERIDINE AND DERIVATIVES. 

Piperidine. — A liquid miscible in water in all proportions, 
having a specific gravity of .881 at degrees C, boiling at 



ORGANIC ACCELERATORS 85 

105.7 degrees C, and smelling like pepper and ammonia. This, 
the prototype of the more recently discovered organic catalyzers, 
was brought out and patented by Bayer & Co. in 1912, for use 
in the manufacture of synthetic rubber, but its extraordinary 
value as an accelerator in connection with natural rubber for 
both hard and soft rubber articles soon overshadowed its orig- 
inal purpose. A mixture of 100 parts Para and 10 parts sul- 
phur that requires an hour to cure at 53 pounds steam pressure, 
may be cured perfectly with only 15 minutes' heating by the 
addition of }£'. part of piperidine. The product obtained from 
this compound contains about 3.5 per cent, of combined sulphur. 
Piperidine may also be used for producing hard rubber by add- 
ing 25 per cent, sulphur. (German patent No. 266,618.) 

Methyl Piperidine. — This active catalyzer boils at 107 de- 
grees C. 

QUINOLINE DERIVATIVES. 

Quinoline Sulphate. — Also known as quinoline sulphonic 
acid. An excellent accelerator yielding good-looking well- 
vulcanized rubber. King suggests that the potassium salt of 
this acid might give better results. 

Quinosol. — This accelerator takes the form of sulphur yel- 
low needles soluble in both alcohol and water. It is manufac- 
tured by Frisch, of Hamburg, Germany, and mixes easily with 
rubber compounds before vulcanization. In a mixture of Peru- 
vian rubber, 12 kilograms; white substitute, 19 kilograms; 
Kaolin (China clay), 2 kilograms; chalk, 5 kilograms, and sul- 
phur, 4.5 kilograms,, the accelerating effect, according to Ditmar, 
is not great, but quinosol acts quite differently when mixed with 
litharge and crude rubber free of substitute, the combined ef- 
fect being greater than the sum of the effects of each employed 
alone. 

Oxiquinoline Sulphide. — This is a satisfactory but too active 
accelerator. It can be used with all sorts of compounds be- 
cause it answers all the needs of the industry. In tests con- 
ducted by Ditmar in collaboration with the Japanese chemist 
Nawa-Naami, a mixture containing Peruvian rubber, 40 kilo- 
grams; brown rubber substitute, 10 kilograms; paraffin, 5 
kilograms; chalk, 41 kilograms; and sulphur, 4 kilograms, re- 



86 ORGANIC AND INORGANIC ACCELERATORS 

quired 2 hours' heating at a pressure of 4 atmospheres (56 
pounds). With oxiquinoline sulphide the mixture was vul- 
canized in 50 minutes. With quinoline sulphate 75 minutes 
were required. Tests of accelerated and unaccelerated prod- 
ucts showed the same breaking point, but the elongation of the 
accelerated product was found to have been reduced one-half. 

MISCELLANEOUS. 

Anthraquinone. — Recommended in 3 to 5 per cent, strength 
in batches containing rubber substitute. In a typical mixture 
containing rubber substitutes it reduces the duration of vul- 
canization from 2 hours to one-half hour. 

Antipyrine. — Acts like anthraquinone. (Ditmar.) 

Naphthylamine. — Acts like anthraquinone. (Ditmar.) 

Urea. — This and such derivatives as guanidine have been 
found useful. (King.) 

Formanilide. — Many patents cover the anilides, such as 
formanilide. 

Thio formanilide. — Cited by King. 

Albumen. — The direct addition of proteins to rubber, as 
described by W. Esch in German patent No. 273,482, Novem- 
ber 22, 1912, presents an interesting possibility. The protein, 
usually egg albumen, 15 parts, is mixed with 2 parts hydrated 
lime or magnesium hydroxide to form a paste. Low grades 
of rubber, when mixed with this paste, dried, sheeted and 
smoked to render the albumen insoluble, are considerably im- 
proved thereby. 

Magnesia. — Marckwald and Frank claim that: 

1. Magnesia affects vulcanization only by forming inter- 
mediate products which accelerate the combinations of sulphur 
with rubber. 

2. Owing to decomposition of the chloride (left in through 
inefficient washing) by exposure to the air, and also during 
vulcanization, magnesium chloride and sulphate form undesir- 
able contents in cold vulcanized goods. 

In cold cure with chloride of sulphur vapor sulphur in the 
mixing has no more immediate influence than any other filler — 
although a later action may perhaps be expected in a warm, 
light warehouse. 



ORGANIC ACCELERATORS 87 

The following accelerating preparations are patented by 
Dr. D. F. Twiss : 

Quicklime slaked with a solution of sodium or potassium 
hydroxide and the resulting soda or potash lime employed as 
a fine powder. Suitable proportions are found to be ten parts 
of quicklime to three parts of sodium hydroxide or four parts 
of potassium hydroxide. By using one per cent, of such a 
powder in a rubber mixing, the alkali hydroxide can be more 
evenly distributed than if used alone. 

Another method is to use the caustic alkali in conjunction 
with an organic solvent such as glycerol. If this is heated to 
about 175 degrees C. to expel superfluous water, the hydroxide 
can be dissolved and alkali glyceroxide obtained. Potassium 
hydroxide is found somewhat preferable for this method and 
also for the quicklime one. One part of potassium hydroxide 
may be used with four parts by weight of glycerol, although 
the proportions may be widely varied. One or two per cent, 
of such a solution may be mixed into rubber uniformly and 
there is no tendency to produce porosity of the rubber; but the 
vulcanization process is greatly accelerated, the effect being 
comparable with that of the strongest organic accelerators. It 
is also noteworthy that the actual quantity of alkali approxi- 
mates closely to the one-half per cent, recommended for the 
most effective organic accelerators and that with a rubber-sulphur 
mixing the resulting vulcanized rubber in both cases possesses 
the same clear, dark, almost semi-transparent appearance. 

A mixture of rubber with five per cent, of the solution, when 
cured for 90 minutes at 40 pounds pressure, undergoes complete 
vulcanization, practically no sulphur remaining uncombined. 
Other organic compounds may be employed for the solution of 
the alkali, such as glycol. As to aging of samples vulcanized 
in the presence of the alkali solution of glycerol, after a lapse 
of three years since vulcanization a certain weakening was ob- 
served, but no greater than in similar mixings containing other 
accelerators. 

The following are trade designations of secret compounds 
used as accelerators, based on ingredients mentioned in this 
chapter: Accelemal, Annex, Anvico, Dry Aniline, Duplex, Ex- 



88 ORGANIC AND INORGANIC ACCELERATORS 

cellerex, M. C. C, Paradin, Tensilite, Velocite, Velosan, Vitami- 
nex, Vulcacit. 

SUMMARY. 

The list of organic vulcanization accelerators employed in 
American rubber manufacturing practice is not as long as the 
foregoing description would indicate. Practical consideration of 
price and demonstrated utility confines the list substantially to 
the following: 

Thiocarbanilide. 
Hexamethylene-tetramine. 
Aniline. 

Accelerene or paranitroso-dimethylaniline. 
Para-phenylene-diamine. 
Aniline was at first the most extensively used accelerator 
but seems to have given place in general usage to thiocarbanilide 
due to the inconvenience of its liquid form and its pronounced 
poisonous nature. 

Thiocarbanilide is offered to the rubber trade under num- 
erous trade names. 

Hexamethylene-tetramine is nearly as popular an accelera- 
tor as thiocarbanilide. It imparts a characteristic firmness and 
snappy quality to vulcanized rubber and in poisonous quality is 
not as dangerous as aniline although responsible for an annoy- 
ing skin irritation particularly noticeable in warm weather. 



CHAPTER VI. 

FILLERS AND INGREDIENTS USED IN RUBBER 
COMPOUNDS. 

India Rubber is compounded for two reasons, the first 
being to reduce the cost without destroying the usefulness of 
the gum, the second being to impart qualities possessed by a 
great variety of mineral, vegetable, and even animal substances. 

Agalmatolite. — A silicate of aluminum resembling soap- 
stone. It has no advantages over talc, silicate of magnesia, or 
soapstone in rubber use. Its specific gravity is about 2.25. 

Alumina. — The oxide of aluminum and a chief constituent 
of clay. Its specific gravity is 4.15. Ordinarily speaking, it is 
a very inert substance, insoluble, and not readily attacked by 
acids. It is best known in the arts under the forms of corun- 
dum, emery, etc. As obtained chemically it is a fine white 
glistening powder, harsh and dry to the touch. Eaton's formula 
for the use of oxide of aluminum in making white rubber was 
india rubber 40 per cent., oxide of aluminum 55 per cent, and 
sulphur 5 per cent. 

Aluminite. — A white clay containing a large percentage 
of aluminum (about 30 per cent.) and a certain amount of 
silica. Its specific gravity is low, and its fusing point 2,400 
degrees F. 

Aluminum Flake. — A natural product (aluminum silicate) 
in the form of a white powder, free from grit, with a specific 
gravity of 2.58. It is a remarkable heat resistant, is inert in 
compounds, and toughens them. It is a partial substitute for 
zinc oxide, both for color and strength. 

Aluminum Oxide. — See Alumina. 

Alundum. — A patented abrasive material made from oxide 
of aluminum or bauxite. 

Amphiboline. — A German earth. When wetted and dried, 
it will not absorb water again. Specific gravity about 3.25. 
It is used in waterproofing, the product being non-inflammable. 
It is mixed with gelatine or size, no rubber being used : 34 parts 

89 



90 FILLERS IN DRY MIXING 

amphiboline, 9 parts gelatine, 2 parts chrome alum, 2 parts am- 
monium sulphate, 53 parts water. 

Anhydrite. — The water-free form of sulphate of lime or 
gypsum, white in color and crystalline in form. Its specific 
gravity is 2.9. It is formed artificially by heating gypsum so 
as to drive off all its water. Gypsum that has been over-heated 
in the preparation of plaster of Paris and that has lost its ability 
to "set" is pure anhydrite. It is used as a filler in rubber com- 
pounding instead of whiting or Paris white. 

Antimony. — See Golden Sulphuret of Antimony, Black 
Antimony, and Kermes. 

Antimony Oxide. — There are really three of these oxides. 
The trioxide, one most useful in the arts, is a snow-white 
powder of the specific gravity of 5.2. It may be obtained by 
treating stibnite or, better still, powdered antimony metal with 
nitric acid, in a current of air sufficient to carry off the copious 
fumes arising during the operation, or by treating the chloride 
of antimony with cold water for several days. A mixture of 
the trioxide with a small percentage of the insoluble peroxide 
may be obtained by melting antimony in a cast iron retort fitted 
with nozzles, through which air may be blown to agitate the 
melted metal. Dense white fumes arise, which may be con- 
densed in suitable chambers into a snow-white powder. This 
is used in coloring dental vulcanite. 

Argillaceous Red Shale. — A shale that has a large amount 
of clay in it is termed argillaceous, and the substance mentioned 
in the heading may be briefly termed clay tinted red with oxide 
of iron. The analysis of argillaceous clay shows : alumina 39, 
silica 46, water 13, iron, magnesia, and lime 2. It was the basis 
of a well-known oil-resisting compound that for years baffled 
imitation. Specific gravity 2.70. 

Arsenic. — A white brittle metal, with a specific gravity 
of 4.7 or 3.7, according to its form. Also a popular term for 
the oxide of arsenic, sometimes called the white arsenic, which 
is a heavy white powder of the specific gravity 3.7. It is 
slightly soluble in cold water and to the extent of 10 per cent, 
in hot water. There are several coloring matters formed from 
arsenic. The most familiar are Paris green; realgar, which is 
red, and orpiment, yellow. The white oxide is rarely used; the 



ASBESTIC— ASBESTOS 91 

red sulphide is, however, often used; the green has been used 
in mechanical rubber goods, but the color was not a valuable 
one. Hancock vulcanized gutta-percha with orpiment, and 
Forster used it in "mosaic work" for floor coverings. An anti- 
fouling composition for ships' bottoms is formed of gutta-percha, 
copper, bronze, and arsenic. Another is formed of : india rubber 
2 pounds, rosin 7 pounds and arsenic 2 ounces. 

Asbestic. — The part of the rock remaining after the richer 
veins of asbestos have been extracted. This remainder is a 
purely fibrous material, clearly showing its origin. For me- 
chanical uses it is ground fine, and for all sorts of fire-proofing 
purposes is valuable and much cheaper than long fiber asbestos. 
It makes an excellent compounding material for asbestos pack- 
ings, etc., in connection with rubber. 

Asbestine. — A pure fibrous silicate of magnesia, called also 
mineral pulp. It is mined near Gouverneur, New York, where 
is the only deposit at present known where magnesia shows so 
distinct a fiber. Apparently the pulverized mineral is a very 
strong white powder, but in actual use it has not much more 
covering quality than whiting. It was at one time used largely 
in the manufacture of rubber shoes, but, aside from being inert 
and a good filler, was probably no better than whiting, while it 
was more costly. It is often used in white goods, in connection 
with oxide of zinc, to make a light weight compound. It is also 
known as agalite and asbestine pulp. Its composition is : silica 
62, magnesia 33, water 4, iron oxide and alumina 1. Specific 
gravity 2.80. 

Asbestos {Amianthus). — A fibrous silicate of calcium and 
magnesia, also called stone flax, salamander's wool (from an 
old belief that it was originally made from the wool of the 
salamander), cotton stone, mountain flax, mountain wood, and 
mountain cork. Its specific gravity is 3.02 to 3.1. An analysis 
of the two best known varieties shows : 

Canadian. Italian. 

Silica 40.92 40.25 

Magnesia 33.21 40.18 

Water of hydration 12.22 14.02 

Alumina 6.69 2.82 

Protoxide of iron 5.77 .75 

Soda 68 1.37 

Potash, etc 22 .15 

Sulphuric acid traces .31 



92 FILLERS IN DRY MIXING 

The longest fiber is possessed by the Italian, which is some- 
times 3 feet in length. The Canadian ranges from 3 to 6 inches 
in length, but it is finer, more flexible, and more easily separated 
than the Italian. The mineral divides itself naturally into three 
classes : the first, coarse, brittle, very plentiful, and cheap ; the 
second, possessing well-defined fibers of a brownish-yellow color, 
fragile, and containing many foreign bodies; the third, with 
pure white silky fibers which can be woven into textiles. A 
notable use to which asbestos has been put is in the production 
of packing and brake linings. Its low heat conductivity renders 
it particularly useful in steam packings, both for cylinder work 
and for joints, while its incombustibility has long caused it to be 
used for fireproofing purposes. There are fibers formed of ser- 
pentine rock which are much used as a substitute for genuine 
asbestos, and answer nearly as well, being, however, shorter in 
fiber and somewhat less durable. 

Atmido. — A snow-white filler of low specific gravity, free 
from organic matter and indifferent to acids. Used in small 
proportions, is said to increase both strength and resiliency in 
soft rubber goods. Used in large proportions, it makes a very 
hard compound, said to resist superheated steam. Of German 
origin. 

Atmoid. — A very light white earthy matter of English 
origin. Analysis proves it to be an almost pure silica — quite 
close, in fact, to infusorial earth. Specific gravity 2.00. 

Barium Carbonate. — See Carbonate of Barium. 

Barytes. — A heavy white mineral that in commerce takes 
the form of a fine white or gray powder. It is obtained by 
grinding the mineral heavy spar, or by chemical means from 
barium chloride. Its specific gravity is 4.5. It occurs in com- 
merce under the names "permanent white" and "blanc fixe." 
The artificially prepared substance is to be preferred to the 
finely ground mineral, on account of its less crystalline form. 
The commercial article should always be examined to determine 
its freedom from acid impurities. Barytes is chiefly used as 
an adulterant for white lead and paints. Thus, Venice white 
contains equal parts of sulphate of barytes and white lead; 
Hamburg white, 2 parts to 2 parts of white lead; and Dutch 
white, 3 parts to 1 part of white lead. It is wholly inert when 



BASOFOR—BLUE LEAD 93 

used as an ingredient in rubber compounding, increases the re- 
siliency of rubber, and is a make-weight. 

Basofor. — A trade designation for a specially precipitated 
barium sulphate or " blanc fixe." Used as an inert filler and 
pigment. See Barytes. 

Black Antimony. — A black powder obtained by grinding 
stibnite or antimony ore. It is a sulphide of the metal and is 
met with more or less pure, as it is often prepared from a high- 
grade ore. The sulphur contained in it is unavailable for vul- 
canizing purposes, and if used in compounding it is necessary 
to add a sufficiency of sulphur to vulcanize. In the purest form, 
black antimony contains about 28 per cent, of sulphur and 72 
per cent, of antimony. It is insoluble in water, but is dissolved 
by muriatic acid or by caustic alkalies. From its solution in 
alkali a fine brown-red powder may be obtained by treatment 
with a dilute acid, and this powder, known as kermes, has the 
same chemical composition as that mentioned above. Its specific 
gravity is 4.6. It was formerly used sometimes as a filler, as 
it was believed to give a soft effect in molded goods. It has 
been almost wholly displaced, however, by cheaper and better 
ingredients. 

Black Lead. — See Plumbago. 

Blanc Fixe or Permanent White. — Artificial barium 
sulphate, specially prepared by precipitation from solutions of 
native barytes. There are several methods giving variations in 
product adapting it to specific purposes. The specific gravity 
is 4.10-4.20. The grain is extremely fine and amorphous. It 
is particularly valuable as a filler and is said to enhance the 
tensile strength of rubber. See Barytes. 

Blue Lead. — Where zinc ores are found in combination 
with galena, or natural sulphide of lead, the two are often 
smelted together with raw coal and slaked lime, producing a 
fume called blue powder, which is sold under the name of blue 
lead. It is an excellent filler, but is not as good as sublimed 
lead, for example, as it does not impart enough resiliency to 
rubber. Its chief merit is its cheapness. A very fine quality 
of blue lead, containing considerable lead oxide, is now on the 
market, but this must not be confused with either of the two 
low-grade articles mentioned in these paragraphs. This blue 



94 FILLERS IN DRY MIXING 

lead is of exceeding fineness, and gives a peculiarly soft finish 
to the rubber. Used in the place of litharge, it materially as- 
sists in the cure, and produces a fine black. As it has a high 
specific gravity, it often displaces barytes. Blue lead is also a 
name given to an artificial aluminous substance occurring either 
as a loose powder or in a concrete form, colored blue by means 
of some kind of blue dye — aniline or logwood — which does not 
contain lead. 

Bone Ash. — See Calcium Phosphate. 

Boneblack. — See Charcoal (Animal). 

Bucaramanguina. — A transparent amber-colored, incom- 
bustible material, found near Bucaramanga, Colombia. It is 
somewhat similar to asbestos, for which it has been mentioned 
as a substitute in the manufacture of packings. 

Burnt Umber. — An earth containing a large amount of 
iron oxide of a dark-brown rust color. As mined, it is called 
raw umber, and the product obtained by calcining it is known 
as burnt umber. It was formerly used in brown packings, and 
to a certain extent, in maroon goods. 

Calamine. — An ore of the metal zinc, and a carbonate of 
zinc. Ordinary calamine, which is a silicate of the metal, has 
a specific gravity of 3.6 to 4.4, and is little used in the arts. 
Noble calamine, or native carbonate of zinc, is a gray or grayish 
yellow to brown powder, according to its priority. Its specific 
gravity is 3.4 to 4.4. Its nature is earthy, and heat has no 
action upon it. A little of it is said to toughen soft compounds. 

Calcium Carbonate. — Very familiar under the native form 
of limestone, marble, or chalk. See Whiting. 

Calcium Phosphate or Phosphate of Lime. — The chief 
constituent of bones, forming the bulk of their ashes when burnt. 
It is a white powder, and when in crystalline mineral form, has 
a specific gravity of 3.18. It is insoluble in ether, alcohol, or 
the benzine class of solvents. As it occurs naturally it is known 
as flour of phosphate and is used in part as a substitute for 
whiting. Bone ash made from animal charcoal is a common 
form used in the same way. 

Calcium Sulphate. — Also called gypsum. A common 
mineral occurring under various forms and names as alabaster, 
selenite, and gypsum earth. It is pure white in color and has 



CALCIUM SULPHATE— CHALK 95 

a specific gravity of 2.33. Plaster of Paris is a calcined form 
of gypsum. In the ordinary recovery of rubber by the acid 
process, whiting becomes changed from carbonate to sulphate 
of calcium, otherwise sulphate of lime. See Plaster of Paris 
and Anhydrite. 

Calcium White. — Another name for whiting. 

Calomel. — A white, inodorous powder of specific gravity 
about 7.2. It is permanent in the air, but should be kept in the 
dark, as light blackens it. When pure, it may be wholly volatil- 
ized by heat. Calomel blackens under the action of alkalies. It 
is insoluble in water, alcohol, ether, or benzine. It is the basis 
of a compound for rendering hose waterproof, the other ingre- 
dients being magnesia, black antimony, oxide of zinc, tar sulphur 
and india rubber. Its function in rubber is to hasten the cure. 

Carbonaceous Clay. — Found near Lake Albert, South 
Australia. After being boiled at a high temperature with caustic 
soda and washed with a weak solution of sulphuric acid, it 
assumes a remarkably light, spongy, elastic character. It is 
used as an absorbent, and as a substitute for cork in linoleum. 
It has been suggested as an ingredient for use in connection with 
rubber for playing-balls, etc. 

Carbonate of Barium. — Known also as witherite; has a 
specific gravity of 4.3. It is a white powder insoluble in water 
and alcohol. See Barytes. 

Carburet of Iron. — A name given to a mixture of graphite 
and oxide of iron. A fine black-brown powder, specific gravity 
4.00, although variable. It makes a fair filler in compounding, 
being inert and strongly coherent. In packings it has been largely 
used, and also in compounds for wagon covers and tarpaulins 
before reclaimed rubber came largely into use. It has also been 
used in cements for card clothing. 

Chalk. — A white, soft, somewhat gritty substance, consist- 
ing chiefly of carbonate of lime. It is made up of myriads of 
very small shells of marine animals long extinct. Its nature is 
earthy; that is to say, it is not easily affected by ordinary bodies. 
Acids disengage carbonic acid gas from it. Its specific gravity 
is 2.9. If heated to a red heat, carbonic acid gas escapes and 
quicklime is left behind. See Whiting. 



96 FILLERS IN DRY MIXING 

Charcoal (animal). — Animal charcoal is made from 
bones distilled out of contact with air and has the property, in 
a high degree, of absorbing odors and soluble coloring matters. 
It is often used, therefore, in deodorizing rubber goods, and 
experimentally by chemists for filtering gutta-percha dissolved 
in bisulphide of carbon, where a perfectly clear product is de- 
sired. Its use is advised by Forster in gutta-percha compounds, 
and by Warne, Jaques, and others for packings to withstand 
heat. Its specific gravity is about 2.85. 

Charcoal (vegetable). — This is a popular term for the 
coal produced by the charring of wood. There are many ma- 
terials which are really charcoals, such as animal charcoal just 
quoted, carbon, coke, graphite, and wood charcoal. All of these 
are practically the same in their pure states, being almost wholly 
carbon. Wood charcoal — that which is meant in rubber com- 
pounding by vegetable charcoal — consists of carbon, hydrogen 
and oxygen, the last two being in the proportion to form water. 
It is black and brittle, insoluble in water, infusible, and non- 
volatile in the most intense heat. It has the power of condens- 
ing gases and destroying odors. Charcoal may or may not be 
a bad conductor of heat and a good conductor of electricity, 
these properties depending upon the wood from which it is made. 
Technically, it is divided into hard wood charcoal and soft wood 
charcoal. Its composition at ordinary temperatures is about as 
follows : carbon 85 per cent., water 12 per cent., ash 3 per cent. 
Specific gravity (powdered) 1.40 to 1.50. It is used in rubber 
compounding in certain vulcanite varnishes and in certain in- 
sulated wire compounds. For the latter use, willow charcoal 
is preferable, as it is a decided non-conductor. It has also been 
used in sponge rubber, with the idea that it acts as a preserva- 
tive in a compound which is very likely to be short-lived. Mac- 
intosh used large quantities of ground charcoal in place of 
lampblack in some of his compounds. A French substitute for 
vulcanite paints or lacquers is made of 10 pounds of bitumen, 15 
parts of charcoal, and a little linseed oil, mixed by heating. 

China Clay. — See Kaolin. 

Compo. — A name for a composition used in rubber manu- 
facture in the United States years ago, but not in use now. 
The name, however, clings to two compounds sold by an 



CORK—DIATOMACEOUS EARTH 97 

English chemical house for use in rubber work. They are of 
a secret nature. No. 1 is used in the manufacture of oil-resist- 
ing valves and in tubing for chemical factories, in the propor- 
tion of 30 pounds of compo to 10 pounds of rubber. No. 2 is 
used for soles for tennis shoes and in mechanical goods, in the 
proportion of 25 pounds of compo to 10 pounds of rubber. 

Cork is the bark of the cork oak, native of Southern 
Europe and Northern Africa. The chief supplies come from 
Spain and Portugal. Cork is the basis of the fine black known 
as Spanish black, which is made by burning the refuse in close 
vessels. In granulated or powdered form, cork has long been 
a favorite ingredient in rubber compounding. Not that it is 
used in any such measure as whiting or barytes, but many mills 
have used it, and a few in large proportions. Used in connec- 
tion with india rubber and gutta-percha, it has been the subject 
of about fifty patents. Its largest use, perhaps, was in the manu- 
facture of kamptulicon, where india rubber is used as a binding 
material, and in linoleum, where oxidized oils are used in place 
of rubber. It was also used in what was known as leather rub- 
ber, in which palm oil distillate, a little india rubber, and a good 
deal of granulated cork were used. At one time it was also 
compounded with rubber and made up into a waterproof felt 
for hats. It also went into compounds to resist heat, into cricket 
balls, and into golf balls, where it was compounded with gutta- 
percha and enough metal filings were added to give the necessary 
weight. A rubber blanket used in special manufacture also had 
its surface covered with granulated cork as an absorbent ma- 
terial. In some cases the cork was charred and roasted to re- 
move what resinous matter might be in it, while in others resin- 
ous matter was removed by boiling in alcohol. In its usual form 
cork has a specific gravity of 0.24. Fine grinding eliminates 
much of the contained air with proportionate rise in specific 
gravity. 

Cornwall Clay. — See Kaolin. 

Corundum. — A mineral which is nearly pure alumina, yet 
of great specific gravity, and of exceeding hardness, being in- 
ferior, in this respect, only to the diamond. Emery (which see) 
is a variety of Corundum. Specific gravity 3.90. 

Diatom aceous Earth. — See Infusorial Earth. 



98 FILLERS IN DRY MIXING 

Electric Finish. — See Farina. 

Emery. — The average composition of emery may be taken 
as alumina 82, oxide of iron 10, silica 6, lime 1^. Its specific 
gravity is about 3.8 to 4. It is prepared by breaking the stone 
at first into lumps about the size of a hen's egg, then running 
it through stamps, and crushing it to powder. It is then sifted 
to various degrees of fineness, and graded according to the 
meshes of the sieve. Emery is next in hardness to diamond 
dust and crystalline corundum, and it is used chiefly as an 
abrading agent. Prior to the invention of vulcanite, emery 
wheels were made by heating clay and emery in suitable molds, 
thus vitrifying them like common earthenware. In rubber mills 
it is chiefly used in the manufacture of what are known as vul- 
canite emery wheels. It is also used in grinding and sharpening 
compounds, as hones and strops. (See also Alumina and Cor- 
undum.) A certain amount of it also gives the desired surface 
to rubber blackboards. 

Farina. — This is sometimes used in small quantities in 
unusual mixtures as a compound, but has little value, as there 
are many better substitutes for it. A practical use for it, how- 
ever, is the brushing of a rubber surface with it before vul- 
canization, when it is necessary to have printing or stamping 
done upon that surface afterwards. Farina is made largely of 
potatoes, another name for it being potato starch. The process 
consists simply of crushing, sifting, washing, bleaching, and 
grinding, which is repeated three times, and each time the starch 
granules separate and are collected. It has a specific gravity 
of 1.50. Potato starch will be remembered by rubber manu- 
facturers as the material which the gossamer makers used suc- 
cessfully for a number of years in the production of the "elec- 
tric" or "corruscus" finish. Bone ash is used sometimes in the 
place of farina, where rubber surfaces are to be printed upon. 

Feldspar. — A name given to a group of silicates of which 
the principal ones are orthoclase or potash feldspar, containing 
silica, alumina, and potash, and having a specific gravity of 2.5; 
albite, containing silica, alumina, and soda, specific gravity 2.61 ; 
oligoclase, containing silica, alumina, soda, and lime, specific 
gravity 2.66; and anorthite, containing silica, alumina, and lime, 
with a specific gravity of 2.75. The feldspars by the action 



FIRE CLAY— FOSSIL MEAL 99 

of the weather break down into china clay, kaolin, or pottery 
clays. Ground very fine, they have been used in the production 
of rubber enamels and lacquers. 

Fire Clay. — A kind of clay which, better than any other, 
resists the action of heat and direct flame. It is composed prin- 
cipally of silica and alumina, with traces of the alkali earths. 
The best is found in conjunction with coal, and is called Stour- 
bridge clay. Its specific gravity is about 2.5, and its color dirty 
white. Mixed with vulcanized india rubber dissolved in tar oil 
and sulphur, it forms a compound which, when applied to hot 
joints, cures at once. 

Flint is practically pure silica and its specific gravity is 
2.63. The nature of the powder obtained by grinding is always 
sharp and gritty. It is unacted upon by all ordinary means, and 
with difficulty even in the laboratory of the chemist. Its prin- 
cipal use, perhaps, is in the manufacture of glass. Flint varies 
in color from yellow and brown to black. It has been used in 
erasive rubbers, although pumice stone is better. 

Flour of Glass. — Glass powdered and sifted through a fine 
sieve of 150 meshes to the inch. Glass varies much in its compo- 
sition, the more common kinds containing lime, while the so- 
called flint glass contains lead. Potash and soda also enter into 
the composition of glass; hence all flour of glass will contain 
those ingredients which entered into the composition of the glass 
it was obtained from. Its specific gravity ranges from 2.40 to 
3.00 for ordinary compositions. Generally speaking, flour of 
glass may be considered an inert substance under ordinary con- 
ditions, though the softer kinds are attacked even by boiling 
water. It was used by Newton and Wray in insulated wire 
compounds, and has also been used in certain packings. 

Flour of Phosphate. — See Calcium Phosphate. 

Fossil Farina, also called mountain milk, is an earth physi- 
cally similar to infusorial earth. It is obtained from China and 
consists of silica 50y 2 , alumina 26^2, magnesia 9, water and 
organic matter 13, with traces of lime and oxide of iron. It has 
been used in rubber compounding for the production of packings 
and semi-hard valves. 

Fossil Meal or Fossil Flour. — See Infusorial Earth. 



100 FILLERS IN DRY MIXING 

French Chalk. — This is ground and sifted talc, forming a 
white, greasy- feeling powder. Its chemical composition is hy- 
drated silicate of magnesia, the water being chemically combined. 
Its specific gravity is 2.70. See Talc. 

Fuller's Earth. — A kind of clay. It is a greenish or 
brownish earthy, somewhat greasy-feeling substance, having a 
shining streak when rubbed. Its composition is : silica 70, oxide 
iron 2.5, alumina 3.5, lime 6, combined water 16, magnesia trace, 
phosphoric acid trace, salt 2, alkalies trace. Fuller's earth is 
found in extensive deposits in England, where its annual con- 
sumption at one time exceeded 2,000 tons, chiefly in woolen 
manufacture for fulling cloth. Its specific gravity is from 1.8 
to 2.2. It is used in rubber compounding for about the same 
purposes as infusorial earth, and is also used in the manufac- 
ture of rubber type. 

Gold Oxide. — As a matter of curiosity it may be noted 
that this is the most costly ingredient suggested for rubber com- 
pounding. It occurs in two forms — the protoxide, a dark green 
or bluish violet powder, and the teroxide, a brown powder. The 
use of the protoxide was patented by Ninck. For dental vulcan- 
ite it is doubtful if either form of the oxide could be used, even 
if the price were so low as to bring it within reach. Another 
formula calls for the mechanical admixture of gold leaf. 

Graphite. — See Plumbago. 

Gypsum. — See Calcium Sulphate. 

Infusorial Earth. — It is known also as diatomaceous 
earth, Tripoli, fossil meal, mountain flour and kieselguhr. This 
is obtained usually from deposits at the bottom of inland waters, 
and consists of the minute siliceous remains of infusoria or 
microscopical animals. The largest deposits, in the form of a 
fine white or pinkish powder, are found in California, Nova 
Scotia, and in Germany. This earth is a wonderful non-conduc- 
tor of heat, and, in connection with asbestos, is used in the 
manufacture of boiler coverings. It is used also in small pro- 
portions in various rubber compounds, where it increases both 
strength and resiliency, though if used in excess it makes a very 
hard compound. The best grades are wholly free from vegetable 
matter, are nearly pure silica, and perfectly indifferent to cor- 
rosive substances. Under the ^ame of diatomaceous silica it is 



IRON PYRITES— LEAD OXIDE 101 

used in a formula for elastic valve packing. This packing is 
described as practically indestructible in steam or water, oils, 
acids, etc. Specific gravity, 1.66 to 1.95. 

Iron Pyrites. — A natural sulphuret of iron, about 5.20 spe- 
cific gravity, commonly of a bright, brass-yellow color; a very 
plentiful mineral often mistaken for gold. It is used in the 
manufacture of sulphuric acid, while sulphur is also obtained 
from it by sublimation. It was used by Warne, Fanshaw, and 
others, in the manufacture of packings to resist a high degree 
of heat. The sulphur in iron pyrites has also been used in 
vulcanization. Warne, in one of his heat-resisting packings, 
patented the use of iron pyrites, and, in the compound that he 
gives as an example, leaves out the whole or a portion of the 
sulphur usually employed. 

Kaolin. — A white clay largely used in the manufacture of 
porcelain and to a degree in rubber compounds. It is a hydrated 
silicate of alumina. Specific gravity 2.20. 

Kermes. — A brownish-red form of sulphide of antimony, 
artificially prepared by boiling in carbonate of soda. If left to 
itself the solution will partly deposit a very fine powder of 
kermes, while the clear solution may be further treated with a 
weak acid to obtain the remainder. Kermes will not vulcanize 
rubber without the addition of sulphur. Its specific gravity is 
about 4.5. Its composition is 28 per cent, sulphur and 72 per 
cent, antimony. It is rarely used in rubber compounding. 

Kieselguhr. — See Infusorial Earth. 

Lead Acetate or Sugar of Lead. — A white poisonous 
powder soluble in water and alcohol. In its crystalline form 
it contains about 7 per cent, of water of crystallization, which 
is easily driven off at a temperature of, say, 80 degrees to 100 
degrees F. Its specific gravity is : crystallized, 2.3 ; water-free, 
2.5. Its use in semi-hard composition was patented by both 
Goodyear and Payen. India rubber dissolved in oil, to which 
has been added acetate of lead, is used to fill the pores of cer- 
tain leathers so that the "filling" shall not come through. It is 
also used in certain varnishes in connection with gutta-percha. 

Lead Carbonate. — See White Lead. 

Lead Oxide. — See Minium and Litharge. 



102 FILLERS IN DRY MIXING 

Lead Oxychloride. — There are several oxychlorides of 
lead. Their specific gravity may be taken at 7.20. The sub- 
stance once known as Turner's yellow and another known as 
Carsel yellow were both of this composition. More recently a 
white compound has been prepared, which, from its covering 
power, has been used largely as a paint. Tarpaulin compounds 
consisting of india rubber, coal tar, and pitch are treated with 
oxychloride of lead for surface drying, in lieu of vulcanization. 

Lead Peroxide. — The highest oxide of lead — a dark brown 
powder with a specific gravity of about 9.00. It is easily de- 
composed, and from this characteristic it has a strong oxidizing 
action. Exposed to sunlight or to heat, it yields oxygen and 
passes into the lower oxide known as red lead. Its oxidizing 
properties make it a questionable ingredient in compounding 
rubber, although certain formulas call for its presence. 

Lead Sulphate. — A white powder of the specific gravity 
of 6.2, insoluble in water, but readily soluble in caustic alkalies. 
In Cooley's formula for artificial leather, which has gutta-percha 
for a base, it is used in connection with dextrine, magnesia, and 
cotton dust. 

Lime. — The oxide of the metal calcium. It is commonly 
known in two states, viz. : quicklime, which is the pure oxide, 
and slaked lime, which is the hydrated oxide mixed with some 
carbonate. Quicklime is a white solid substance of specific 
gravity 3.2. It is not stable, taking up water and carbonic acid 
from the air and breaking down into a fine white powder, usually 
called air-slaked lime. Its power of absorbing water has caused 
it to be favorably used in drying operations, while the insoluble 
compounds it forms with various oils have led to its being con- 
sidered as a drier, although this action is not properly to be called 
one of drying. Lime, air-slaked (specific gravity 2.40), is used 
in rubber work, where there may be a little moisture in a com- 
pound, which it readily neutralizes. It is also used in soft 
cements in connection with tallow and india rubber, but only 
where the rubber has been melted and the cement is of the non- 
drying variety. In compositions like that of S Orel's, lime is 
introduced to effect a combination between resin acids found in 
the resin and resin oil. Excess of lime in india rubber is in- 
jurious, because it renders the compound too dry, thus indue- 



LITHARGE— LITHOPONE 103 

ing oxidation. When used in small quantities, aside from its 
effect upon moisture, it combines with free sulphur and modifies 
its continued action upon the rubber. It must be remembered, 
however, that lime diminishes the resiliency of india rubber, 
while it increases the hardness of both hard and soft rubber. 
It may be used in small quantities in insulated wire, and in a 
measure assists the insulating capacity of the rubber. Rubber 
also cures quicker when compounded with lime. 

Litharge. — One of the oxides of the lead, known as the 
monoxide. When pure its specific gravity is 9.36. Commercial 
litharge often contains carbonic acid gas and water taken up 
from the air. These may be removed by strong heating. It has 
a peculiar property, the nature of which is yet a debated ques- 
tion, by virtue of which it renders oil more easily oxidized, or, 
as it is commonly called, rendered dry. There is no reason to 
suppose that this action is available with caoutchouc. The best 
litharge is made from pig lead, which is placed in a reverbera- 
tory furnace and exposed to a current of air, which burns it to 
an oxide. It has been noted in rubber factories that certain 
men seem sensitive to the effects of litharge, often developing 
symptoms of lead poisoning. Persons who show any symptoms 
should pay scrupulous attention to personal cleanliness. It is 
said that such persons have been cured by taking them out of 
the mixing room entirely, and putting them to work on vulcan- 
izers, particularly where they open and handle the goods from 
the finished heat, the theory being that the sulphur fumes neu- 
tralize the effects of the lead. Possibly there is a grain of 
wisdom in this, for the old-fashioned treatment for lead poison- 
ing was sulphur baths and the drinking of water acidulated with 
sulphuric acid or the acid sulphate of magnesia. Litharge is not 
only a valuable filler for rubber, but has the faculty of hastening 
vulcanization in a marked degree. In other words it is an 
accelerator. All dry heat goods depend upon it, and in mold 
work and general mechanical goods it is used whenever possible. 
Of course, it is generally available for dark or black effects 
only. 

Lithargrite. — A substitute for litharge, made of a mixture 
of pulverized and calcined magnesia and oxide of lead. 
Lithopone. — See Colors. 



104 FILLERS IN DRY MIXING 

Magnesia. — A calcined white dry powder which, with water, 
forms a hard, compact mass like marble. Its specific gravity is 
3.65. It is earthy in its nature, having no taste, but producing 
a sense of dryness in the mouth, owing to its absorption of 
moisture. It is frequently called calcined magnesia from the 
method of preparation by burning magnesia alba. Its use in 
rubber is to increase its toughness and resiliency, which it does 
to a marked degree when used in moderation. Magnesia is also 
used in the production of compounds like balenite, its use in 
hard rubber compounds being to increase resiliency as well as 
hardness. A very small quantity of it is also used in compounds 
for insulated wire, where it is said to increase the insulating 
qualities of rubber. Carbonate of magnesia occurs native in the 
mineral magnesite and, in connection with carbonate of lime, 
as dolomite. 

There exist two kinds of calcined magnesia: the heavy and 
the light calcined. Heavy calcined magnesia is produced by cal- 
cining heavy carbonate of magnesia, which carbonate is won by 
precipitation of hot magnesia solutions by hot solutions of soda. 
The light calcined magnesia is produced by calcining the light 
carbonate of magnesia, and this light carbonate is the precipi- 
tation product of magnesia solution together with soda solutions, 
both carefully cooled. The difference between kinds of calcined 
magnesia concerns only the structure, so that light calcined mag- 
nesia in a dry state seems to have a very big volume, but if the 
included air is expelled, the big volume cannot have the expected 
effect, if light calcined magnesia is kneaded together with india 
rubber on the mixing rollers. The vulcanization of india rubber 
can easily be accelerated by addition of calcined magnesia. Such 
an addition is often necessary with soft rubbers in open steam- 
cured compounds. Rubbers with a high amount of resins, such 
as Guayule, Cameroons, Assam, Borneo, etc., usually give better 
results if compounded with appropriate additions of calcined 
magnesia. 

Manganese Peroxide. — Another name for black oxide of 
manganese, which is a black powder having a specific gravity 
of 4.8. It is not readily acted on in ordinary ways, being un- 
changed by heat short of bright red. It is insoluble in the 



MARBLE FLOUR— MINERAL WOOL 105 

ordinary hydrocarbon solvents. Solvent naphtha was treated 
with peroxide of manganese by Humphry to free it from water. 

Oxides of manganese have a destructive effect on rubber, 
and blacks that contain this, as they sometimes do, are to be 
avoided. Manganese is used in connection with pitch, turpen- 
tine, and gutta-percha for making Brandt's cement. 

Marble Flour. — This is the finely ground chips of white 
marble, composed almost wholly of carbonate of lime. It is a 
heavy inert powder used in rubber compounding as a substitute 
for barytes. It has also been used to some extent in hard rubber, 
and in the manufacture of hones. Specific gravity 2.65 to 2.75. 

Massicot. — A monoxide of lead (lighter yellow than lith- 
arge). Specific gravity 7.90. A higher degree of oxidation 
turns this into a product called minium or red lead. It is often 
used in rubber compounds, acting practically like litharge. 

Mica is the name given to a group of complex silicates 
containing aluminum and potassium, generally with magnesium, 
but rarely with lime. Their specific gravity ranges from 2.8 to 
3.2, while their color varies greatly. Ground mica is simply one 
or other of these micas reduced to powder. It is used in rubber 
compounding chiefly for insulating purposes. It is handled as 
a cement, compounded with rubber, and cut with benzine, or 
may be mixed dry on the grinder. It is also used in fireproof 
coverings in connection with rubber, and it is said that for a 
semi-hard result that is to come in contact with hot water, rubber 
and mica form the best compound. Mica in a state of a very 
fine powder is also known as " cat's gold " or " cat's silver." 

Mineral Wool. — Produced by sending blasts of steam 
through molten slag, which reduces the fluid metal to a fiber 
similar to the fused glass that is spun into glass silk. Natural 
mineral wool, such as is found in the Hawaiian Islands, is very 
brittle, but the artificial has considerable toughness. It is also 
known as slag wool, or silicate cotton. It appears in light fleecy 
masses, and at a distance looks like fine cotton batting. It is 
very cheap, but is easily affected by weak acids, and should be 
kept away from a moist atmosphere. It has not been largely 
used in rubber work as yet, but Lascelles-Scott strongly advises 
its use, giving as reasons its cheapness and its physical fitness. 
The sulphides present in it also assist in vulcanization. 



106 FILLERS IN DRY MIXING 

Minium. — See Red Lead. 

Mountain Flour. — See Infusorial Earth. 

Orange Mineral. — A red lead made from carbonate of 
lead, while red lead is made from litharge. As a general rule, it 
contains some lead carbonate. It differs from red lead in color, 
in that it is more orange red, and more brilliant. The reason 
for this difference is that it is less crystalline, its particles being 
much finer than those of red lead. The pigment is also more 
bulky and much smoother. It is used in finer grades of dark 
rubber, to assist the cure and impart resiliency. Its specific grav- 
ity is 6.95. 

Ossein. — A light powder made from specially treated bone. 
Said not to be affected by acids. Is not affected by heat and is 
not hygroscopic. Preparation patented in England by J. F. 
Hunter. 

Pagodite. — A mineral resembling steatite or soapstone. Its 
name comes from its having been used in the East as a material 
for carving miniature temples or pagodas from, as it is soft 
enough to be cut with a knife. Its specific gravity is the same 
as that of soapstone (about 2.70), and its color greenish white. 
See Agalmatolite. 

Paris White. — This has exactly the same composition as 
whiting, but is a much harder and more compact form of 
English chalk, and therefore has greater density. Spanish white 
is a coarser variety of the same material. Its uses are practi- 
cally the same as those of whiting. Specific gravity 2.70. See 
Whiting. 

Permanent White. — See Blanc Fixe. 

Petrifite. — A white powder composed of two inexpensive 
but secret substances. When mixed with water it solidifies 
quickly, and is an excellent binding substance. Mixed with 
marble dust, it is sometimes melted and cast upon glass or other 
smooth surfaces-, and makes an excellent table-top in place of 
the zinc tables used in many rubber factories. As it is perfectly 
impervious to ordinary solvents, neither cement nor india rubber 
sticks to it. It is manufactured in England. 

Phosphorus. — A non-metallic element or metalloid, al- 
though in its combining relation it is more closely connected 
with arsenic and antimony than with any members of the sul- 



PHOSPHORUS— PLASTER OF PARIS 107 

phur group. It is found ordinarily in two states — the ordinary- 
phosphorus and the red variety. Ordinarily phosphorus is an 
almost colorless or faintly yellow substance, somewhat resem- 
bling wax, and giving off a disagreeable odor. It fuses at 111.5 
degrees F. into a colorless fluid. Heated in the air to about 
140 degrees F., it catches fire and burns with a bright white 
flame. It dissolves freely in benzol, bisulphide of carbon, and 
in many oils. Red phosphorus is an amorphous powder of a 
deep red color, with no odor, and may be heated to nearly 500 
degrees F. without fusing. Its specific gravity is 2.10. It does 
not take fire when rubbed, undergoes no change on exposure to 
the air at ordinary temperatures, and is far less inflammable 
than ordinary phosphorus. It is insoluble in solvents of the 
ordinary phosphorus, and is not poisonous. Mulholland made 
an insulated wire compound from shellac and india rubber in 
solution, combined with one to two per cent, of phosphorus, 
which he cured with chloride of sulphur. As cold-cure gums 
are of little value as insulators his invention is of doubtful value. 
He also made a preparation of india rubber, resin and tallow, 
and shoddy, to be applied in a fluid state where gas came in 
contact with rubber, adding phosphorus after his solution was 
finished, to prevent decomposition of the rubber. Duvivier also 
treated gutta-percha with sulphide of phosphorus, claiming that 
he got an elastic result, but allowing that his compound was 
damaged by acid vapors, to neutralize which action he mixed 
carbonate of soda with it. An anti-fouling preparation of 
English origin was also made of gutta-percha, turpentine, and 
a little phosphorus. 

Pipe Clay. — A peculiar kind of clay containing neither iron, 
sand, nor carbonate of lime. It is beautifully white, retaining 
its whiteness when burnt. Its specific gravity is 2 to 2.5. It 
was used by Mayall in combination with gutta-percha, india 
rubber, zinc, shellac, and resin for insulating tape, and by Austin 
G. Day to absorb gases during vulcanization. 

Plaster of Paris. — This is prepared by calcining gypsum 
or sulphate of lime. Its properties of hardening when made into 
a paste with water are well known. It is used sometimes in- 
stead of lime in compounding and also for making trial molds 
for rubber work. It was used in old-fashioned dry heat com- 



108 FILLERS IN DRY MIXING 

pounds to prevent blistering. Specific gravity 3.2. See An- 
hydrite. 

Plumbagine. — A dark-colored pigment manufactured in 
England and sold to rubber manufacturers for the production 
of valves. By its use the rubber is vulcanized and goods made 
which are said to resist successfully the action of cheap lubri- 
cants. One pound of plumbagine is used to two pounds of 
rubber. 

Plumbago. — This sometimes is called black lead, though 
having no relation to lead ; it is also called graphite. Its specific 
gravity is 2.1 to 2.2. Its color is black and shiny. It consists 
chiefly of carbon, but contains more or less alumina, silica, lime, 
iron, etc., varying from 1 to 47 per cent., but not chemically 
combined. Black lead is a perfect conductor of electricity. It 
is more incombustible than most ingredients used in rubber com- 
pounding, and is capable of withstanding great heat. It is used 
in the rubber industry, chiefly in the manufacture of what are 
known as graphite or plumbago packings. It is a wholly inert 
substance, safe to use in connection with any compounds, and 
is not affected by heat or acids, alkalies, or corrosive substances. 
It is useful also in certain polishing compositions made with india 
rubber as a base. Almost all German asbestos cements contain 
a proportion of finely powdered graphite. 

Portland Cement was first obtained by burning the mud 
found at the mouths of several large rivers in Europe with a 
pioportion of clay and lime. Its composition is somewhat com- 
plex, containing: lime 55 to 63 per cent, silicic acid 23 to 26 
per cent., alumina 5 to 9 per cent., and oxide of iron 2 to 6 per 
cent., together with magnesia, potash, soda, sulphate of lime, 
clay, or sand in various small proportions, according to the mode 
of manufacture. Its specific gravity is 3.00-3.10. Its value as 
a cement depends upon the interaction of the lime and the silicic 
acid. In compounding it would have no chemical effects upon 
rubber, but might of itself become much hardened and thus 
cause mechanical injury to goods in which it has been intro- 
duced. As it occurs commercially, it is a gritty powder of a 
gray-brown or yellow-brown color. Its only use as far as known 
in rubber is where it is mixed with tar oil and waste rubber 
to joint pipes containing fluids. 



POWDERED COAL— RED CHALK 109 

Powdered Coal. — Coal consists chiefly of carbon, and is 
universally regarded as being of vegetable origin. Various coals 
differ widely in their composition and characters, running from 
the softest kinds of earths to compact and solid bodies like par- 
rot coal, which is so compact and solid that it has been made 
into boxes, inkstands, and other articles which resemble jet. The 
average specimen of coal analysis is : carbon 82.6, hydrogen 5.6, 
oxygen 11.8. Some curious compounds of india rubber and coal 
have been formed. One, for instance, was a mixture in which 
two pounds of waste india rubber in a cheap solvent was mixed 
with nearly a ton of powdered coal (specific gravity 1.25-1.75), 
which contained some clay and peat, the use being for an arti- 
ficial fuel; another use was in the production of hard rubber. 

Pumice. — A light, porous, ashy stone, specific gravity 2.20- 
2.50, the product of volcanic action, its structure being that of a 
mass of porous glass. Its composition is a mixture of silicates 
of aluminum, magnesia, calcium, iron, potassium, and sodium, 
varying with the particular lava whence it had its origin. Its 
action on india rubber will be quite inappreciable, chemically 
speaking, but its mechanical action will be that of a sharp cut- 
ting powder. Ground fine, it is used in the manufacture of 
erasive rubber, and is also used compounded with the rubber in 
the manufacture of hones. Recent patents call for its use in 
certain semi-hard compounds, its presence being said greatly to 
increase their toughness. Mixed with lard oil to a thick paste, 
this has been used for polishing india rubber. 

It is particularly valuable for use in the dry-heat cure of 
such articles as water-bags and bottles. The goods filled, bedded 
and covered with fine pumice powder are evenly cured without 
discoloration or change of color. In this respect pumice is 
superior to talc for the purpose, and the goods are more easily 
washed clean. 

Puzzolana. — A porous lava found near Naples, used 
chiefly, when mixed with ordinary lime, in forming hydraulic 
cement. Compounded with marine glue, it is used as a varnish 
for preserving metallic articles from corrosion. 

Red Chalk. — Artificially deposited chalk colored by any 
suitable pigment — usually one of the red oxides of iron. See 
Chalk. 



110 FILLERS IN DRY MIXING 

Red Lead. — An oxide of the metal, which is also known as 
minium. Prepared from pure massicot or from white lead. Its 
specific gravity is 8.6 to 9.1. A scarlet crystalline granular pow- 
der, of rather strong coloring powers. As a colorant in rubber 
work it would be unavailable, since the sulphur necessary to 
vulcanize would render it more or less black, owing to the 
formation of sulphide of lead. It is sometimes used, how- 
ever, in place of litharge. It is also used in "hot" cements 
of gutta-percha and for varnishes such as those made of india 
rubber, linseed oil, etc., for covering the backs of mirrors. See 
Minium, Massicot, and Orange Mineral. 

Rotten Stone. — Usually considered to be the residuum of 
naturally decomposed impure limestone, and varying in compo- 
sition with its sources. Specific gravity 1.98. That from Derby- 
shire, England, shows much alumina; other sorts have more 
silica. The name is sometimes incorrectly given to " Tripoli," 
which is a species of infusorial earth. It can have no particular 
action on rubber, as it is very inert, but it is used in certain pack- 
ings, and was also used by Warne in insulated wire compounds. 

Selenium. — A non-metallic element or metalloid of a dark- 
brown color, analogous to sulphur. Specific gravity 4.80. It 
has no smell and is a non-conductor of electricity. It occurs 
rarely in nature, being found chiefly as a selenide in combination 
with lead, silver, copper, or iron. It is the basis of an unused 
process for vulcanizing india rubber. 

Silex. — Pure silica. See Flint. 

Silica. — The oxide of the metal silicon, familiar in the 
forms of flint, quartz, etc. Its specific gravity is 2.6. It is with- 
out action on india rubber, except mechanically speaking. It is 
used in Chapman's vulcanite enameling solution, made of india 
rubber, sulphur and silica. See Flint. 

Silicate Cotton. — See Mineral Wool. 

Slag Wool. — See Mineral Wool. 

Slaked Lime. — See Lime. 

Slate. — A soft, laminated, argillaceous material, chiefly 
aluminous in composition, and allied to the clays. Finely ground, 
it makes a good semi-hard valve of a blue-gray shade. It has 
been also used in general rubber compounding. Specific gravity 
2.70. 



SOAPSTONE—TALC 111 

Soapstone. — A silicate of magnesia, combined with more 
or less alumina and water. It is really a massive form of talc. 
In color it is white, reddish, or yellow, is soft and greasy to 
the touch, is easily cut, but is hard to break. Its specific gravity 
is 2.26. It is used often in the place of French talc, for keeping 
rubber surfaces from sticking together during vulcanization, and 
also for burying dark colored goods and holding them in shape 
while they are being cured. Used as an adulterant for rubber, 
it makes an excellent semi-hard compound for valves. It is also 
used as a basis compound in the manufacture of insulated wire. 
See Talc. 

Starch. — A vegetable substance allied closely to cellulose. 
It occurs in regular lumps composed of granules which have a 
definite character, according to the variety of the plant from 
which they were derived. When dry its specific gravity is 1.53. 
Commercial starch contains usually about 18 per cent, of water 
and, if kept in a damp place, will absorb 33 per cent, of water. 
It was much used formerly on solarized work. Torrefied starch 
is obtained by roasting the common form, and is used in arti- 
ficial leather compounds. 

Sublimed Lead. — A white lead known as sublimed lead is 
used very largely in rubber manufacture. It is a fine white 
amorphous powder and imparts a decided toughness to rubber 
compounds. It acts both as a filler and chemically. Its peculiar 
velvety fineness makes it mix intimately with the rubber, and 
gives a very fine finish, showing no shiny crystals on the sur- 
face. The oxide of lead in the sublimed lead will also bind 
free sulphur in the rubber. The amorphous state of the sub- 
limed lead makes the action of the lead oxide in this much more 
effective than the action of litharge, and the result is a very 
smooth, lively, jet-black rubber. Specific gravity 6.20. 

Sugar of Lead. — See Lead Acetate. 

Talc or French Talc is a mineral allied to mica. It is 
composed entirely of silica and magnesia, in the proportions of 
67 to 73 of silica, 30 to 35 of magnesia, and 2 to 6 of water. 
Specific gravity 2.70. Its colors are silvery white, greenish 
white, and green. Talc slate is more like steatite and is used 
for similar purposes. French talc is used very largely in rubber 



112 FILLERS IN DRY MIXING 

factories in all lines of work for preventing surfaces from stick- 
ing together, during either manipulation or vulcanization. It is 
also used commonly for dusting molds to prevent the gum from 
sticking to the metal and extensively to bury white goods and 
keep them in shape during vulcanization. It is used sometimes 
in compounding, but any great amount of it produces a stony 
effect. It makes, however, an excellent semi-hard packing. It 
is used further in compounds for soft polishing, with india 
rubber as a binding material. 

Talite. — A white earthy material used in general rubber 
compounding. It is allied to diatomaceous earth, presumably, 
and has the same usage. Its analysis shows : Moisture 5.59, 
silica 83.9, sesquioxide of iron 1.2, alumina 2.8, oxide of man- 
ganese trace, potash trace, combined water and organic matter 
(by ignition) 6.47, loss and undetermined 0.04 — total 100. 

Tin Oxide. — The form most frequently used in the arts 
is the dioxide. This is a white water-free powder, of the specific 
gravity of 6.7, insoluble in acids and such solvents as naphtha, 
petroleum, etc. It is infusible, except at a very high temperature, 
tasteless and inodorous. French oxide of tin is a carefully pre- 
pared and purified form of the dioxide. It is rarely used in 
rubber work, although Newton recommends it for a basic in- 
gredient in rubber type. The other oxides of tin are at present 
merely of chemical interest. 

Tripoli. — See Infusorial Earth and Rotten Stone. 
Tyre-lith. — A trade designation for collodial barium sul- 
phate. See Blanc Fixe. 

Wheat Flour is used in making matrices for rubber stamp 
work, and sometimes as a compounding material in india rubber, 
though this is not to be advised, as the flour is apt to sour. A 
standard low grade of wheat flour known as "red dog" is particu- 
larly suited to the purpose of dusting the skim coating of wool 
linings, because, owing to its peculiar texture, it is easily remov- 
able by a wash of thin cement in the making-up process and 
does not impair the adhesion to another rubber surface. 

A large and important use for it has been in the dusting of 
black goods, such as rubber coats, so as to keep them from stick- 
ing together, should they accidentally touch during the dry heat 



WHITE LEAD-WHITING OR CHALK 113 

of vulcanization. Wheat flour is preferable to almost anything 
else, for the reason that it washes off after vulcanization, with- 
out leaving any trace in color or stain. It is used on the goods 
known as " dull finished." 

White Lead. — This is a mixture of hydrated oxide and 
carbonate of lead and is a heavy white powder. It is unstable 
in color, however, as sulphur compounds, especially in the 
gaseous forms, easily attack it and blacken it by reason of the 
formation of sulphide of lead. Its specific gravity is 6.46. 
Sometimes it is adulterated with lead sulphate, chalk, carbonate, 
or sulphate of baryta, or pipe clay. The simplest test for the 
purity of white lead is to heat it in a thin glass vessel with some 
very dilute pure nitric acid; if pure it will dissolve completely. 
If chalk be present it also will pass into the solution, in which 
it may be detected by the addition of caustic potash, throwing 
it down as a white cloud. The best white lead is made by the 
old-fashioned Dutch process, which consists of packing the 
metallic lead, cast in the form of buckles to present a large sur- 
face for corrosion, in covered earthen pots, in the bottom of 
which is placed acetic acid. The pots, thus prepared, are stacked 
and buried in a mass of spent tan bark to conserve the heat 
caused by the reaction of the volatile acid on the metal. The 
original " triple compound," patented by Goodyear, consisted of 
india rubber, sulphur and white lead. 

Whiting or Chalk, as it is often called, is carbonate of 
lime. It is a white earthy material of the specific gravity of 
2.7 to 2.9. It is made from English chalk, which is crushed, 
floated, and run through a filtering process, and dried in cakes 
made in varying degrees of fineness by a system of dry grind- 
ing and bolting. Where whiting is kiln-dried hastily, or under 
extreme heat, it is apt to become calcined, which gives it a hard, 
gritty feeling. Air-dried whiting is considered the best. Whit- 
ing is in reality a purified form of carbonate of calcium, of a 
very soft or flocculent quality. The finest grades are known as 
"gilders' " and "extra gilders'." It is used more generally in 
rubber compounding than any other material, except sulphur. 
Used moderately, it increases the resiliency of rubber, but adds 
to the hardness. It does not, however, produce the stony effect 



114 FILLERS IN DRY MIXING 

that many ingredients give. The molds used in rubber-stamp 
making are composed of whiting, wheat flour, glue, and carbolic 
acid. Whiting is liable to absorb considerable quantities of water 
from the air. It is customary in many mills, therefore, to keep 
it in large bins that not only are covered but have steam pipes 
in the lower portions to drive out any moisture from the material. 

Witherite. — See Carbonate of Barium. 

Zinc Oxide. — See Colors. 

Zinc Sulphate or White Vitriol. — The crystals contain 
about 44 per cent, water of crystallization. Specific gravity 2.03. 

Zinc Sulphide. — See Colors. 

UNUSUAL INGREDIENTS IN DRY MIXING. 

It is not strictly accurate, perhaps, to say that it is unusual 
for fibers to be incorporated in rubber mixtures, for stocks made 
from unvulcanized rubber clippings have been used for years. 
Inner soles for rubber footwear and mats, and molded articles 
have long been made of stocks of this kind, the fibers being 
cotton (as cotton linters) and wool, chiefly. Where wool was 
present there was oftentimes danger of blistering from the oil 
in the fiber, but this was easily gotten over by special compound- 
ing. In addition to the fibers already noted, silk, flax, jute and 
hemp — in fact, almost all of those in ordinary use — have been 
utilized, being added to the compounds to give toughness to them. 
The goods in which they are usually put are packings, gaskets, 
artificial leather, tire treads, shoe soles, and other wearing sur- 
faces. 

A fiber that has attracted considerable attention for this 
work, and one for which a number of patents have been granted, 
is coconut fiber, which is recommended for packings. Certain 
kinds of moss have also been used, as have sponge cuttings, peat, 
and wood pulp. This last-named material has been used both 
in packings and in insulated wire compounds. It is also the 
basis of a curious artificial rubber that appeared several years 
ago, under the name of maltha, but is not to be confused with 
the product that has become almost universally known by that 
name. 

Sawdust of all kinds has also been incorporated in rubber, 
and was formerly used in making sponge rubber, until better 



UNUSUAL INGREDIENTS IN DRY MIXING 115 

compounds were discovered. Those who use vegetable fibers 
prefer them unbleached rather than bleached, and very often 
treat them to remove resins that may be present. A few of the 
many other vegetable substances that have been used are sugar 
and sugar charcoal and seaweed. 

Animal substances are also valuable, as for instance, animal 
charcoal, whalebone, which is specified in some of the Woodite 
patents, fur, tan-hair, leather fiber, currier's skivings, which are 
used in artificial leather, the white of eggs, glue, etc. 

Under the head of earthy and metallic ingredients, almost 
anything can be used, although some metals have a bad effect on 
rubber, notably copper and manganese. The unusual earthy 
matters are powdered fossil iron-stone, Wisconsin mineral, coke 
ashes, Stourbridge clay, powdered granite, salt, powdered litho- 
graphic stones, powdered oyster shells, powdered schist; and 
in metals, steel, and all other common metal borings, filings, and 
turnings. These latter have been incorporated in packings as 
a rule. One packing in particular, which has had a world-wide 
reputation, was heavily compounded with brass filings. 

Deodorization of Rubber, and the neutralization either 
of the smell of the rubber or its solvent, has brought out also 
a curious line of ingredients. Musk, for example, has been 
used to disguise the earthy odor of gutta-percha. Alcoholic 
infusions of sage-tea, lavender, and verbena have been used in 
fine goods, while in powdered form, ginger root, birch, orris root, 
sassafras, marshmallow root, sandal wood, and other sweet- 
smelling ingredients have been incorporated. The leaf of the 
mint has also been mingled with copperas and placed in dry 
heaters, while a more expensive process was that pursued by 
Hill, who passed a current of hot air over perfumes and into the 
heaters. It must not be imagined that the ideas expressed in 
the foregoing are unworthy of the consideration of those who 
make ordinary cheap mechanical goods, for certain of these in- 
gredients are used today in mechanical mixtures to overcome the 
odors of African rubbers. Essential oils and gums are also used 
for the same purposes, the descriptions of which will be found 
under their proper departments. 



116 FILLERS IN DRY MIXING 

Medical science has also added its list of ingredients to 
rubber compounding, chiefly in the line of adhesive plasters, 
where ingredients like dry mustard, menthol, capsicum, bella- 
donna and a great variety of other medicaments are incorpo- 
rated with the rubber. 



CHAPTER VII. 

SUBSTITUTES FOR INDIA RUBBER, NATURAL 
AND ARTIFICIAL. 

Rubber Substitutes, as a rule, are made from oxidized 
oils. Those used most generally are made from linseed, rape- 
seed, cottonseed, mustard, peanut, or corn oils, acted on either 
by chloride of sulphur or by sulphur boiled with the oil at a 
high temperature. Substitutes have been known over fifty years, 
and have been made the subjects of many patents, but only 
within the last twenty-five years have they come into general 
use. The fact that Europeans were unable at first to get the 
results with reclaimed rubber that were secured in the United 
States, led them to go further in their experiments with oxidized 
oils and to exploit their uses more thoroughly. The substitutes 
on the maket today are, as a rule, white, brown, and black. 
They are often of the same specific gravity as pure india rubber, 
so that their presence cannot be detected in rubber compounds 
by specific gravity tests. Substitutes of this type are easily 
analyzed and the results of such analyses are of value to rubber 
manufacturers. The table on the next page, containing analyses 
of typical substitutes, is adapted from Dr. Robert Henriques.* 

It would be a mistake to suppose that rubber substitutes 
are of no value, for they possess certain very distinct advan- 
tages not found in simple mineral adulterants nor possessed by 
the bituminous products now in use. Their value, of course, is 
where they cheapen stock without seriously injuring its dura- 
bility or changing its texture. Where substitutes are com- 
pounded with rubber they are used in small quantities, sometimes 
only 5 per cent, being added, and rarely is more than 25 per 
cent, to be found in good compound. 



* "Journal of the Society of Chemical Industry," 1904, page 47. 

117 



118 



SUBSTITUTES FOR RUBBER 



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AD AM ANT A— A. R. D. GUM 119 

The list in the accompanying table has been made quite com- 
prehensive, not because all the substitutes described are deemed 
valuable, but rather to give a broad view of the subject. It will 
be noticed that many of these gums are far out of the line of 
sulphurized oil experiments. Resins, glues, asphalt, cellulose, 
seaweed, bastard rubbers, animal substances, etc., have all been 
called upon and some of the treatments have been as original 
as the ingredients are unusual. To the end that the perfect sub- 
stitute may be found, and with the fullest appreciation that any- 
thing which suggests new experiments has its value to the manu- 
facturer, many that otherwise would be ignored are given here. 

Adamanta. — A substitute for india rubber, made from lin- 
seed oil, sulphur, lime, and resin. It is a thick, black, gummy 
mass, with an odor similar to that of most of the sulphur oil 
substitutes, and showing a bright cleavage. It was at one time 
used largely in France and Germany, and introduced to some 
extent into the United States. Its chief use was in cheap me- 
chanical rubber goods, and for insulation. 

Adhesor. — A sticky substitute used to a certain extent in 
frictions. 

Algin Gum. — A gluey, leathery substance, manufactured 
from seawood. It is insoluble in cold water, alcohol, ether, and 
glycerine, and combines readily with alkaline and metallic bases 
to form substances, many of which are soluble. Algin can be 
used for waterproofing compounds, as it combines easily with 
rubber, shellac, and other gums. With many metallic bases it 
forms insoluble compounds as tough as horn or as pliable as 
gutta-percha. It is an English product. 

Amber-resin Substitute. — An English patented substitute 
made of amber-resin dissolved in castor oil, heated with a little 
sulphur. Is treated with ozonized air after cooling. The mass 
then treated with chloride of sulphur in the presence of a solvent, 
calcium carbonate being also added. 

A. R. D. Gum. — So called because it is used as an anti-dry- 
rot compound. It is manufactured of 112 parts glue, 56 parts 
resin, 10 parts boiled linseed, and 35 parts water. In some cases 
it has also been mixed with india rubber in general compound- 
ing. Patented by J. F. Ebner, London, England. 



120 SUBSTITUTES FOR RUBBER 

Artificial Elaterite. — Made from liquid bitumen by in- 
corporating with it vegetable oils, such as cottonseed oil, palm 
oil, rapeseed oil, etc. The product is treated with the aid of heat 
and pressure, with chloride of sulphur, saltpeter, and sulphur, 
which produces an oxidization of the fatty substances. The re- 
sult is an elastic rubber-like or leathery mass, which is soft, 
spongy, and gluey. This gum is said to be far more elastic than 
the best samples of mineral rubber, and is useful for waterproof- 
ing and insulation. Patented by W. Brierly, in England. 

Artificial Gutta-percha. — A French compound made of 
50 parts copal, 15 parts sulphur, 30 parts turpentine, and 60 
parts petroleum. While mixing the heat reaches 100 degrees 
C. ; it is then cooled to 35 degrees C. Then there is added a 
solution of 3 parts casein, in weak ammonia, and a little 
methylene, and reheated to 120 degrees C. It is then boiled 
with a 15 or 20 per cent, solution of tannin, and 15 parts am- 
monia. After several hours' boiling it is washed and cooled. 

Asbestonit. — An asbestos product manufactured in Eng- 
land under a secret process, for use as steam or hot-water 
packing. 

Astrictum. — A compound to be used in damp places, con- 
sisting of pulped cotton 15 pounds, pitch 25 pounds, asphalt 20 
pounds, ground granite rock 20 pounds, bitumen 5 pounds, resin 
10 pounds, coal tar 12 pounds, and mastic 5 pounds. 

Belledin's Process for Leather Impregnation. — Hides 
are treated in alkaline solutions and immersed in a bath of 
rubber solution. 

Borcherdt's compound for dolls' heads consists of 5 pounds 
glue, 10 pounds sugar, 2y 2 pounds glycerine, 3 pounds Perry's 
white. 

Black German Substitute. — Made of boiled linseed oil 
and sulphur, together with resinate of lime. This gum is similar 
to adamanta, and has been practically driven out of the market 
by lighter substitutes. 

Blandite. — An artificial india rubber invented by Dr. A. 
L. Blandy, of London. It is fairly elastic, stretching to about 
twice its length, and returning readily. It is very pliable and 



CAOUTCHENE—CHRISTIA GUM 121 

does not show signs of cracking- when bent. It is vulcanized 
like ordinary rubber, and can be molded into any form desired. 
Coated on cloth, it strongly resembles leather. It is water- 
proof, and is used for gas tubing, mats, etc. In its crude form, 
it is a liquid mass resembling molasses. Dr. Blandy's patent 
describes the compound as made preferably of linseed oil which 
has been reduced by oxidation ; then 10 per cent, of bisulphide 
of carbon to which has been added 10 per cent, of chloride of 
sulphur, is mingled with the oil, and the mixture brought by 
gentle heating to the desired consistency. Trinidad asphalt, 
cleansed and reduced to powder, is combined under the heat in 
the proportion of 3 parts to 1 of oil. Care must be taken to 
avoid fire in heating. These proportions are gradually brought, 
by heat and stirring, to a liquid or thin state, and when in this 
condition it must be poured upon a wet, cold surface, and thus 
cast into sheets, convenient for subsequent mixings. 

Caoutchene. — A French substitute consisting of 100 parts 
sunflowerseed oil, 25 parts chloride of sulphur, and exposed to 
air ten days, when it becomes yellow and elastic. To this is 
added matesite, a Madagascar gum, and then isoprene is added. 

Caoutchite. — Vulcanized rubber exposed to heat (250 de- 
grees F.) for several days and devulcanized and recovered by 
this means alone. 

Carrol Gum. — A well-known sulphur oil substitute used in 
the United States. In smell it has all of the characteristics of 
the sulphurized oil products. It is produced usually in granular 
form, and is very black. 

Cereal Rubber. — Wheat treated with ptyalin. The inven- 
tion of William Threnfall Carr, of England. It is a gluey 
product which, after it comes from the so-called vulcanizing 
press, is said to be both plastic and waterproof. 

Chicle Substitute. — A specially prepared cottonseed oil 
substitute. Said to be very largely used by manufacturers of 
chewing gum. See Gum-carbo. 

Christia Gum. — An English substitute for gutta-percha 
or india rubber, used as a surgical dressing. It is said to be 
composed of hemp fibers, so treated as to be impervious to both 



122 SUBSTITUTES FOR RUBBER 

alcohol and water. Dieterich analyzed a sample of the product, 
and said that the fibers were sulphite wood pulp, and that the 
coating was made from chrome gelatine treated with glycerine, 
or the well-known compound of glue, glycerine, and bichromate 
of potassium. 

Con-current Rubber. — Invention of Julius Nagel, of New 
York. A secret compound, the basis of which is linseed oil and 
resins. 

Corkaline is made of glue, glycerine, ground cork, and 
chromic and tannic acids. It is of English derivation and is 
used as a substitute in mat work. 

Cork Leather. — A French invention composed of thin 
sheets of cork, covered on both sides with an extremely thin 
india rubber skin, and of a textile fabric outside. It is very 
light, is a good insulator against heat, and is waterproof. 

Corn Oil Substitute. — A sulphurized oil substitute simi- 
lar to that made from oxidized linseed or rapeseed oils, manu- 
factured from corn or maize oil. It is the cheapest oil sub- 
stitute that has yet been put on the market. It is made in two 
colors, brown and straw, and is used in large quantities in me- 
chanical goods and in proofing. A good example of this type 
of substitute is that known on the market as " Kommoid." 

Dankwerth's Russian Substitute. — This is said to be a 
perfect substitute for both gutta-percha and india rubber, and 
is used for covering telegraph cables. High temperatures do 
not affect it. It is made of 1 part by weight of the mixture of 
equal parts of wood tar and coal tar oil, with 2 parts of hemp 
oil heated until the mass is of the right consistency. Then 1.3 
by weight of boiled linseed oil is added. To this is added a little 
ozocerite and spermaceti. It is then heated again, and finally a 
little sulphur is added. 

Dermatine. — A well-known substitute for india rubber and 
leather, made of an artificial gutta-percha called " gum percha," 
7 pounds; powdered waste rubber, 7 pounds; india rubber, 14 
pounds; sulphide of antimony, 6 pounds; peroxide of iron, 2 
pounds ; flour of sulphur, 4 pounds 8 ounces ; alum, 4 pounds 8 
ounces ; asbestos powder, 2 pounds ; sulphuret of zinc, 3 pounds ; 



DOEBRICH'S COMPOUND— ELASTITE 123 

carbonate of magnesia, 7 pounds. A little change in this com- 
pound adapts it for machine belts. A variety of colors is gained 
by mixing in various pigments in place of sulphuret of antimony 
or peroxide of iron. The invention is patented by Maximilian 
Zingler, of London. It is claimed that dermatine will stand more 
wear than either leather or rubber, that it is absolutely unaffected 
by heat, cold, dryness, or moisture; and that it will stand per- 
fectly the action of grease, oils, or acids. Adaptations of the 
formula given above permit it to be manufactured in molded 
forms. It is used for valves, packing, etc., and also for covering 
insulated wire. 

Doebrich's Compound for dolls' heads consists of 1 pound 
glue, y 2 pound glycerine, y 2 pound sugar, and 1 tablespoon ful 
pulverized flour, with a little albumen and coloring matter. 

Durate. — An artificial rubber compound said to be similar 
to dermatine. 

Ekert's High Pressure Composition. — Consists of rubber, 
asbestos fiber, litharge and sulphur. To this base are added 
oxide of zinc, iron oxide, graphite, magnesium silicate and resin. 
It is patented. 

Elasteine. — An elastic substance produced from solid and 
semi-solid copal resins and oleic acid, which entirely dissolves 
them. The product is soluble in spirits of turpentine and in oil. 
This solution of gums in oleic acid gives an opportunity to pro- 
duce materials that have sometimes the elasticity and the con- 
sistency of india rubber. The inventor advises their use in in- 
sulating wire and in various kinds of proofing. It is of French 
origin, patented by M. Louis Riviere. 

Elastic Glue. — A mixture of dry glue and glycerine in 
equal parts, by weight. As little water should be used as pos- 
sible in its manufacture. It is used for elastic figures, galvano- 
plastic molds, etc. It is not waterproof, nor will it stand a high 
degree of heat. 

Elasticite. — Trade name for an American corn oil sub- 
stitute. 

Elastite. — A brown rubber substitute of German origin of 
the sulphur oil type. 



124 SUBSTITUTES FOR RUBBER 

Endurite. — The invention of John Stuart Campbell, of 
England. The basis of it is rubber and it is used in golf balls, 
belting, etc. 

Euphorbia Rubber. — J. G. Boles reduced Euphorbia gum 
to a fine powder and, after drying carefully at a low tempera- 
ture, put it in solution and finally hardened it by mixing it with 
earthy matters and shellac. 

Fayolles' Substitute. — A French substitute for water- 
proofing, made as follows: 1 part sulphuric acid, 1 part gly- 
cerine, \y 2 parts formalin, 1 part phenol. 

Fenton's Artificial India Rubber. — Manufactured from 
linseed or similar oils, mixed with tar, pitch, or other pyro- 
ligneous products, the mixture being placed in a bath of diluted 
nitric acid, and allowed to remain until, by the action of the bath 
upon the compound, the whole is coagulated into a tough, elastic 
magna. The black "Fenton" contains as coloring matter a small 
quantity of plumbago or black carbonate of iron. The gum is 
patented by Ferrar Fenton, London, England. In his specifica- 
tion he modifies it by taking the artificial gum described, and 
placing it in a bath composed of a solution of sugar of lead, 
oxide of zinc, saltpeter, or some other form of nitrate, and, if 
high flexibility is desired, adds 5 to 10 per cent, to copal gum 
and nitric acid diluted with water. These solutions are used one 
at a time, the proportion being 5 per cent, of sugar of lead, or, 
for greater hardness, 5 to 7^2 per cent, of saltpeter to the weight 
of the magna. Before vulcanizing, the substances are washed in 
an alkaline solution to remove acid. Fenton rubber is said to 
have been subjected to 320 degrees F. for fifteen minutes, the 
only result being to increase its elasticity. 

Fibrine-Christia Gum is manufactured just as Christia 
gum is, except that silk fibers are used in the place of hemp. 

Fig Juice Proofing. — A French composition made up of 
fig juice, Brazilian tapioca, and pearl moss, together with vulcan- 
ized rubber. Used as a preservative and proofing compound. 

Firmus. — An English rubber substitute presumably of the 
sulphurized oil order. 



GUTTA-PERCHA SUBSTITUTES 125 

Franklin Substitute. — A mixture of coal tar and boracic 
acid dissolved in alcohol. Boiled and oxidized. 

French Gutta-percha. — This gum is made by boiling the 
outer bark of the birch tree in water. The result is a fluid, 
which is very black, and which becomes compact and solid on 
cooling. It has been claimed that it possesses all of the good 
properties of gutta-percha, and that in addition it does not 
oxidize when exposed to the air. Its application for industrial 
purposes has been patented. 

Frost Rubber. — Another name for what is practically 
sponge rubber made from any ordinary unvulcanized rubber 
compound by the addition of a little alum or carbonate of am- 
monia. 

Grape Rubber. — A plaster produced from the skins and 
seeds of grapes from which wine has been extracted by pressure. 

Griscom^s Substitute. — A substitute composed of equal 
parts of animal fat, candle tar, and a residual product from 
petroleum, together with sulphur in proportions of from 2 to 
8 per cent, of the mass. 

Gront and Moore's Repair Cement. — A mixture of un- 
vulcanized stamp rubber in benzine solution to which are added 
turpentine and collodion. 

Gum-carbo. — Substitute made from cottonseed oil. Used 
in general rubber compounding. 

Gum Fibrine is made of paper rags treated with liquid 
carbonic acid, mixed with resin, gum benzoin, and castor oil, 
dissolved in methylated alcohol. It is an English compound. 

Guttaline. — A substitute for india rubber and gutta-percha, 
manufactured as follows : To Manila gum tempered with ben- 
zine is added 5 per cent, of Auvergne bitumen, also mixed with 
benzine. Then add 5 per cent, of resin oil, and allow 48 to 
86 hours to pass between treatments. The product obtained 
is. similar to india rubber. If it be too fluid, the addition of 4 
per cent, of sulphur dissolved in bisulphide of carbon will act 
as a remedy. 

Gutta-percha Substitute. — Formula: 2 parts paraffin, 2 
parts pitch, 2y 2 parts Chinese wood oil, 1.1 parts chloride of 
sulphur, 0.1 of sulphur. Heat to 100 degrees C. for one hour. 



126 SUBSTITUTES FOR RUBBER 

Harmer's Substitute. — Composed of 150 pounds waste 
rubber, 50 pounds Pontianak, 8 pounds African flake, 10 pounds 
substitute. Patented. 

Heveenite. — Another name for heveenoid. 

Heveenoid. — This is claimed to be more insoluble, durable, 
and pliable than almost any other rubber composition. Soft 
heveenoid consists of india rubber 32 parts, camphor 32 parts, 
lime 1 part, and sulphur 8 parts. Hard heveenoid is made of 
india rubber 6 parts, camphor 4 parts, glycerine 1 part, and 
sulphur 16 parts. Heveenoid is the invention of Henry Gerner, 
of New York, and is patented in the United States and Europe. 
Kauri gum is also in certain heveenoid compositions. One 
special advantage claimed as to the use of camphor is that the 
chemical compound termed sulphide of camphor is produced, 
and therefore the rubber does not bloom. 

Hydrocarbon Rubber. — The invention of Eugene Turpin, 
of England. Made by heating a vegetable oil, oxidizing by air 
current, adding 25 per cent, by weight of resin, 25 per cent, pow- 
dered sulphur, 5 per cent, spirits of turpentine, and 1 to 2 per 
cent, carbon chloride. 

Hydrolaine. — One of the original waterproof fabrics made 
by means of india rubber dissolved in spirits of turpentine and 
spirits of wine in equal quantities, and deodorized by oil of 
wormwood. 

India Rubber Leather. — A compound produced by Nelson 
Goodyear in which fibrous substances were mixed with india 
rubber to form a body, the surface of which resembles leather. 

Insulite. — A preparation made of wood or vegetable fiber, 
finely ground and desiccated, and saturated with a mixture con- 
sisting of melted asphalt, incorporated with substances of the 
resin type, with or without substances of the paraffin or anthra- 
cene types. The products resulting are used as substitutes for 
india rubber, particularly in insulation. Patented by Alfred H. 
Huth, London. 

Ireson's Packing Compound consists of a mixture of rub- 
ber, ultramarine blue, and silicate of magnesia. 

Jackson's Compound for Printers' Rollers. — Sixteen 
pounds glue, 16 pounds glycerine, 1 pound borax, 1 pound japan. 



JOHNSTONE'S COMPOUND— KERITE 127 

Johnstone's Non-drying Compound consists of gutta- 
percha, resin, and carnauba wax. 

Jones's Substitute. — An English substitute made of treated 
pseudo gums. Marketed by the Rubber Substitutes Syndicate, 
Limited, of London. 

Jungbluth's Compound. — Calcium carbonate 75 per cent., 
Trinidad asphalt 20 per cent., selenite 5 per cent. In place of 
Trinidad asphalt, neutralite, an asphaltic material made in Ber- 
lin is sometimes used. 

Just's Acid-proof Composition is composed of linseed oil, 
gutta-percha, sulphur, rosin, shellac, and asphaltum or pitch. 

Kamptulicon. — An india rubber compound for floor cover- 
ings. The simplest English formula is a vegetable fibrous ma- 
terial ground into a coarse powder, mixed with india rubber, 
and treated with a cheap solvent, such as coal tar or naphtha. 
Coloring matters are added, if desired. Another kamptulicon 
compound is : gutta-percha, cheap grade, 6 pounds ; reclaimed 
rubber, 12 pounds ; residuum from distilling palm oil, 6 pounds ; 
ground cork, 4 pounds; ground chalk, 2 pounds; sulphur, 
6 pounds; hair, 1 pound; oxide of zinc, 1 pound. 

Kelgum. — A linseed oil preparation manufactured in the 
following way: First, boiling linseed oil in a nitric acid bath 
until it reaches a gum-like condition; second, subjecting the 
gum to a bath for the removal of the acid; third, cutting the 
gum in a solvent bath; fourth, disintegrating the gum with 
the solvent; fifth, grinding the disintegrated mass; sixth, boil- 
ing the material; seventh, subjecting the same to another boil- 
ing, and adding a drier. Used in proofing compounds. In- 
vented by Henry Kellog, United States. 

Kerite. — A compound of vegetable oils, coal tar, bitumen, 
and sulphur, to which are added sometimes a little camphor and 
various waxes. Occasionally sulphide of antimony is used in 
place of sulphur. Vegetable astringents such as tannin, the 
extract of oak bark, etc., are also used in small quantities to 
impart toughness. Kerite is the invention of Austin G. Day, 
and has been used largely for the manufacture of a covering 
for insulated wire. A later patent taken out by W. R. Brixey, 



128 SUBSTITUTES FOR RUBBER 

changes the original kerite compound somewhat. Cottonseed oil 
is eliminated and talc added. The later compound is as follows : 

KERITE. 

Coal tar 25 pounds. 

Asphalt 15 pounds. 

Heat together to 350° F. for y 2 hour ; then add— 

Linseed oil 70 pounds. 

Heat again to 350° F. for 7 hours ; let stand over 
night; heat up to 240° F., and add— 

Sulphur 10 pounds. 

Heat up to 320° F. in y 2 hour and add — 

Sulphur 4 pounds. 

Heat again to 300° F. and add — 

Talc 56 pounds. 

Keep at same temperature J4 to 34 hour, when 
vulcanization will have taken place, and the 
mixture can be poured into molds or allowed 
to cool in mass. 

Kirrage Compound. — A well-known English patented com- 
pound, which takes its name from the inventor. It comes in 
two forms. The first, to be used not over 200 degrees F., is 
composed of india rubber 12 pounds, gutta-percha 4 pounds, 
Stockholm tar 25 pounds, chalk 60 pounds, hemp 4 pounds, and 
sulphur 10 pounds. The same inventor also recommends the 
following, to withstand a great heat and pressure: india rubber 
20 pounds, tar 25 pounds, coke, finely powdered, 25 pounds; 
Stourbridge clay 25 pounds, sulphur 10 pounds, fine emery 25 
pounds, and steel filings 5 pounds. 

Kommoid. — See Corn Oil Substitute. 

Leatherine is a compound that closely resembles derma- 
tine, and in fact a part of the first patent on that product. It 
is intended as a substitute for leather cloth and is made as fol- 
lows : india rubber 28 pounds, substitute 10 pounds, sulphuret of 
antimony 13 pounds, peroxide of iron 4 pounds, sulphur 3 
pounds, sulphuret of zinc 10 pounds, carbonate of magnesia 23 
pounds, and sulphate baryta 8 pounds. 

Leatherubber Compound. — Made of ground waste rubber, 
leather and reclaimed rubber. Manufactured largely in Aus- 
tralia. 

Leonard's Substitute. — Consists of a mixture of corn oil, 
castor oil, chloride of sulphur, naphtha, and oxide of magnesia. 

Liconite, produced in Holland, is described as a mixture 
of bitumen and various oils, without india rubber or gutta- 



LIMEITE—MAPONITE 129 

percha, elastic and tough, and is claimed to be unaffected by- 
water, dilute acids, and alkalies, and neither flows nor cracks in 
ordinary temperatures. 

Limeite. — A cement that is manufactured from melted 
india rubber, with the addition of 8 per cent, of tallow, with 
sufficient slaked lime to give it the consistency of soft paste. The 
addition of 20 per cent, vermilion causes the mass to harden 
immediately. 

Linoxin. — An insoluble oxy-compound produced by the 
oxidation of certain drying oils boiled in acetone or acetic acid, 
from which is produced an elastic mass similar to india rubber. 
Of French origin. 

Luft's Celluloid Rubber. — By boiling equal parts of 
phenol and 50 per cent, formaldehyde with sulphuric acid and 
to the washed and dried product adding india rubber, a com- 
pound is formed that, boiled in alkaline solutions, is transparent 
and similar to celluloid. 

Lugo. — A rubber substitute patented in England, made by 
heating a mixture of oxidized oil and rubber to a temperature 
at which the rubber dissolves. Potassium permanganate is 
added, and the whole heated to 360-400 degrees F. Finely 
divided waste rubber is added, the mass being stirred and the 
temperature maintained. To obtain a harder product sulphur 
may be added. 

Lugo Rubber. — An artificial oxidized oil substitute that 
once had a large sale. It was black, of about the same specific 
gravity as india rubber, and made, in connection with rubber, 
excellent mold work. 

Madanite. — A binding material for smooth surfaces, such 
as air-pumps, etc., made of 2 parts by weight of vaseline, and 1 
part india rubber, melted. This mixture may be left for years 
without perceptible alteration. A low-grade gum used in the 
same way in connection with vaseline makes an excellent insulat- 
ing tape, and has also been used as a friction gum. 

Maponite. — A substitute for india rubber and gutta-percha, 
claimed to be capable of use in the manufacture of golf balls, 
tobacco pouches, etc. It is said to be vulcanizable at 260 degrees 
F. An English patent was applied for by F. E. MacMahon. 



130 SUBSTITUTES FOR RUBBER 

Metalined Rubber. — A name used for compounds used in 
dental work, under a process patented by C. S. Leadbetter, Man- 
chester, England, for strengthening- the gum with a metallic 
fabric, woven or knit. 

MINERAL RUBBERS. 

So-called mineral rubbers are chemically classed as hydro- 
carbons. This term is a convenient designation for any com- 
pound containing only hydrogen and carbon. Certain groups 
of such bodies, both native and artificial, have been for years 
in common use as ingredients in rubber mixtures. 

The adaptability of these bituminous substances to rubber 
compounding is due to their possessing to a greater or lesser 
degree certain physical resemblances to india rubber, especially 
plasticity and a low melting point. These characteristics permit 
the bitumens to be combined easily with rubber and earthy mat- 
ters and in this way very considerably assist the mixing of other- 
wise overcompounded or utterly unmixable stocks. Such hydro- 
carbons being practically proof against oxidation and inert to 
chemical action, are entirely harmless as affecting the durability 
of the stock. They may be credited with actually having a bene- 
ficial effect, inasmuch as they not only add plasticity to the stock 
and retard its rapid drying before vulcanization, but they fill the 
space otherwise occupied by, and exclude much of, the air which 
is always included to a considerable extent in every rubber mix- 
ing. By thus excluding air, the hydrocarbons practically lessen 
internal oxidation and in consequence the durability of the goods 
is increased. It has been demonstrated experimentally that cer- 
tain of the solid "mineral rubbers" actually increase the tensile 
strength in mixings under favorable conditions. 

There is a recognized place and value for both liquid and 
solid hydrocarbons in the manufacture of rubber stocks, but they 
ought always to be considered as "assistants" rather than as sub- 
stitutes for rubber, which they are not. 

Among the bituminous substances usually referred to as 
mineral rubbers are the following hydrocarbons, the specific 
gravities of which are about 1.05: 

Elaterite. — A natural mineral bituminous hydrocarbon. 

Elateron. — A hydrocarbon combination, in granular form, 



ELATERON— NOVELTY RUBBER 131 

blending with crude rubber without depreciating the peculiar 
properties of the latter. 

Emarex. — A product of a semi-elastic material similar to 
elaterite which by chemical treatment is made stable and tract- 
able. It is wholly neutral, is free from sulphur and acids, and 
does not vaporize under heat. Is largely used in rubber com- 
pounding. Marketed in granular form. 

Genasco Hydrocarbon. — A product made from natural 
high-grade asphalt so treated that it is valuable in rubber com- 
pounding. 

Gilsonite. — Lustrous black, hard bitumen. Found in Utah. 

Grahamite. — Dull black solid bitumen. Found in West Va. 

Kapak or Raven Mineral Rubber. — A product made from 
treated elaterite. Used in general rubber compounding. 

La Belle's Mineral Rubberv — A treated elaterite pro- 
duced by an inventor in Utah. 

Liquid Rubber. — A compounding material for mechanical 
rubber goods, friction and cement stocks. It is said to be a 
synthetic composition of that class of terpene substances which 
belong to the caoutchouc family and react with sulphur in the 
same way that rubber does. In appearance, it is a lustrous, 
viscous liquid and extremely sticky. 

Pioneer Mineral Rubber. — One of the first successful 
asphaltum rubbers used in connection with rubber compound- 
ing. It unites perfectly with any grade of crude rubber or with 
reclaimed rubber. Is said to prevent blistering, and to minimize 
the harsh action of free sulphur; is acid proof. 

RUBBER SUBSTITUTES. 

Moroccoline. — An imitation leather made from a secret 
compound which presumably has india rubber for its base. Made 
in various colors, but chiefly as an imitation of Morocco leather. 

Nigrum Elasticum. — A sulphurized oil substance appar- 
ently made from linseed oil. Very dark colored and quite hard. 
Of English origin. 

Novelty Rubber. — An English substitute invented by David 
Lang. It is made in red and drab colors. It comes in small 
slabs about 18 inches square and 2 inches thick, weighing about 



132 SUBSTITUTES FOR RUBBER 

7 pounds. It is said to be easily mixed with ordinary rubber, 
vulcanized in the usual way, the price being about the same as 
for reclaimed rubber. 

Ohmlac. — A hydrocarbon put up in different consistencies 
to suit varying compounding needs. 

Okonite. — A well-known compound for insulating wires 
and cables. According to an English analyst, it consists of india 
rubber 49.6 per cent.; sulphur 5.3 per cent.; lampblack 3.2 per 
cent.; zinc oxide 15.5 per cent.; litharge 26.3 per cent.; and 
silica 0.1 per cent. 

Oxolin. — An English invention patented by Charles J. 
Grist, an electrical engineer, and identical with "perchoid" in 
the United States. This gum is used for waterproof sheeting, 
printers' blankets, packings, etc. It is made of a solution of 
partially oxidized oil by adding litharge and heating to over 400 
degrees F. Jute, or other fibers, is then dipped in the oil, the 
surplus oil is removed in a hydro-extractor, and the oil remain- 
ing on the fibers is oxidized by a current of air. These opera- 
tions are repeated twice. The material is then ground with sul- 
phur and coloring matters, and treated like india rubber. 

Paragol. — A high-grade corn oil substitute. 

Parkesine. — Made from a compound of linseed oil and 
pyroxyline, and used in the manufacture of small articles that 
are sometimes made of hard rubber. A parkesine compound for 
molding, proofing, etc., is as follows: To 500 pounds water add 
50 pounds sulphuric acid, and steep it in as much cotton, or rags, 
or jute, or linen as the liquor will moisten, for 3 or 4 hours. 
Take out, drain, and expose the mass to steam heat of about 280 
degrees F., for an hour, if cotton or jute fiber has been used, and 
3 hours if flax. Neutralize the acid pulp with a bath of water 
and soda, using 4 pounds of carbonate of soda to every 200 
pounds of rags. Wash and press, pass through a coarse sieve 
of 12 meshes per inch, and dry. Grind the granulated material 
and sift it through a sieve of 120 meshes to the inch. The re- 
sulting powder may be mixed, in all proportions up to equal 
parts, with fresh rubber. Compounding 25 to 50 parts dry 
parkesine, with 50 parts alcoholic solvent. A proofing com- 
pound is: 1 pound paraffin, linseed oil, or other drying oil; 4 
to 8 ounces parkesine. 



PEDRYOID—PURCELLITE 133 

Pedryoid. — A rubber-like finish for cloth, made presumably 
of oil, in tan, brown, olive, and other colors, and used chiefly 
in shoe finishing. 

Pensa's Rubber. — A French substitute made as follows: 
100 parts of boiling coal tar, petroleum tar, oil of turpentine, or 
mineral oils, and 25 parts of boric, or phosphoric acid dissolved 
in alcohol, and the vapors are ignited, and the flame extinguished 
as soon as a green color is seen. The mixture is then heated 
at 60 degrees C. in the presence of oxygen, until a viscous duc- 
tile substance is obtained. 

Perchoid. — See Oxolin. 

Peroxide Substitutes. — Peroxide of lead having been rec- 
ommended as a better drier than other oxides used in connec- 
tion with all compounds, the following formulas are given : 25 
parts of walnut oil, 62 parts linseed oil, 5.5 parts peroxide of 
lead, 7.5 parts sulphur. One of greater toughness is composed 
of 25 parts walnut oil, 56 parts linseed oil, 5 parts peroxide of 
lead, 6 parts sulphur, 6 parts gum juniper. 

Pickeum Substitute. — This is made by the following 
treatment of Pickeum gum: 

A 

Boiled linseed oil 160 pounds. 

Vaseline 20 pounds. 

Bastard gum (or Pickeum gum) from Central 

America, cut fine 40 pounds. 

Stir and heat to 250 degrees to 300 degrees F., until the 

gum is dissolved. Then cool to 100 degrees F., and strain. 

B 

(Solution as above 5 gallons. 

Protochloride of sulphur 9 pounds. 

Bisulphide of carbon 9 pounds. 

After the chemical action takes place, the mass is granu- 
lated and the grains are washed and stored for use, or the mate- 
rial may be masticated in a rubber mill and run into sheets for 
use. 

Purcellite. — The invention of Dr. C. Purcell Taylor, of 
England. An insulating substance somewhat similar to gutta- 
percha, but costing much less. It is said to be very tough and 
elastic, may be made of any color, and is either flexible or rigid. 



134 SUBSTITUTES FOR RUBBER 

The specific gravity of the material is 1.2. It can be molded or 
vulcanized like india rubber. Its insulation resistance is equal 
to that of gutta-percha. It is unaffected by atmosphere, by alka- 
line or acid liquids, freezing mixtures and the like. 

Quinn's Rubber. — An English substitute made from petro- 
leum, bisulphide of carbon, chloride of sulphur, and rapeseed oil. 

Rathite. — -A mixture in which waste silk fibers are incor- 
porated with india rubber to impart resiliency and durability. 
About 6 ounces of silk are used with 28 pounds of rubber com- 
pound. It is employed in making tires, pump valves, packings, 
etc. Patented by A. I. Rath, Cheshire, England. 

Resinolines. — Substances so called by Eugene Cadoret, of 
Paris, who obtains them by saponifying various oils by the use 
of a metallic carbonate, using by preference carbonate of lead, 
then decomposing by nitric acid, decanting, and saturating with 
an alkali. The soap thus formed is treated with acid to form a 
resinoid body, purified by dissolving in alcohol, and evaporating 
the solution. Resinolines thus formed are very similar to natu- 
ral resins. They are either semi-fluid, pasty, or solid. When 
solid, they are remarkable for their flexibility. 

Rhea Gum. — Rhea fiber washed and dried; immersed in a 
solution of silicate of soda ; then carefully dried ; then immersed 
in a bath of resin or other heavy hydrocarbon oil at a tempera- 
ture of about 275 degrees F. ; then put in a hydro-extractor 
which is worked at a temperature of 300 degrees F., when the 
superfluous oil is extracted; the mass is then dried. Later it is 
mixed with gums, resins, india rubber, or gutta-percha, and rhea 
gum is the result. 

Rice Rubber. — Japanese or Machi rice treated so that it 
makes an elastic cellulose product. 

Rosaline. — A vegetable product said to contain about the 
same chemical elements as india rubber, and of about the same 
specific gravity. Manufactured in the United States, France, 
and England. A strong point is made by the manufacturers 
that after vulcanization no chemist is able to detect that there 
is anything but pure rubber in a mixture containing 25 per cent, 
of rosaline and 75 per cent, of india rubber. In vulcanizing, it 



RUBBERAID—RUBEROID 135 

requires about one-third more time to bring about the usual 
result. 

Rubberaid. — An amber-colored substitute manufactured 
from cottonseed oil by a secret process, which removes what 
the inventor calls the grease, leaving an elastic semi-solid which 
has been used quite largely in compounding. 

Rubber Asphalt. — For road making, a late French patent 
covers a mixture of rubber and asphalt, that after intimate 
mixture takes the form of a powder. This is laid hot and under 
test is very cheap and lasting. 

Rubber Flux. — A semi-fluid compound of a dark color 
and presumably made from non-drying, non-volatile oils. It is 
used in compounding where the stocks are dry, in place of palm 
oil, for example. Is said to prevent oxidation and bloom. 

Rubberic. — Fiber blended with india rubber in solution, 
stretched, and dried. Used chiefly in making rubber tires and 
mechanical goods. Patented by William Golding, Manchester, 
England. 

RuBBERiTE. — An artificial rubber of the same specific grav- 
ity as fine Para. In color, elasticity, capability for vulcanization, 
and durability, it is said to resemble the higher grades of rub- 
ber. It is the invention of H. C. B. Graves, London, England, 
and is made up as follows: 

Trinidad asphalt 47 to 80 per cent. 

Oxidized oil 20 to 30 per cent. 

Vaseline 5 per cent. 

Sulphur 15 per cent. 

Chloride of sulphur 3 per cent. 

Rubber Velvet. — Manufactured by sprinkling powdered 
felt of a variety of colors over proofed cloth before vulcaniza- 
tion. The result is a velvet-like fabric, elastic and waterproof. 

Ruberine. — An American rubber-like solution used as an 
insulation paint, and also as a proofing mixture, and partaking 
of many of the qualities of ruberoid. It is also manufactured 
in Germany. 

Ruberoid. — An American substitute for india rubber that 
has the physical appearance of a high grade of black oil sub- 
stitute. In use, however, it differs from many of them, for the 



136 SUBSTITUTES FOR RUBBER 

reason that it has been found useful in vulcanite compounds, 
while at the same time it may be used in ordinary soft rubber 
work. 

Rub-hide. — This is a patented composition made from raw 
hide. It is very rubbery in consistency. 

Russian Substitute. — Manufactured from the skins of 
rabbits and other small animals, or the waste therefrom, digested 
in crude glycerine, and a little water. The formula is 3 parts 
by weight of the cleansed substance melted in water, with 3 
parts by weight of crude glycerine, to which is added % part 
by weight of a concentrated solution of potassium chromate. 
The resultant mass is flexible. To make it harder, a little less 
glycerine and more chromate of potash are required. To with- 
stand acids, 30 per cent, of gum lac dissolved in alcohol is added. 
For waterproofing fabrics, % part by weight of oxgall is added, 
with enough salt water to give it the consistency of oil. 

Sarco. — A rubber assistant, probably made from treated 
elaterite. 

Soap Substitutes. — These have been exploited and ex- 
plained more thoroughly by Professor W. Lascelles-Scott than 
by anybody else. The typical formulas that he gives are as fol- 
lows : 28 parts of aluminum soap, 60 parts of linseed oil, 8 parts 
of acid free sulphur, 4 parts of oil of turpentine. Another, to 
use in connection with reclaimed rubber, is 15 parts of aluminum 
soap, 25 parts of devulcanized rubber, 60 parts fresh rubber, 
benzine quantum sufficit. Another still, in which a low grade 
pseudo-gutta is used, is 15 parts aluminum soap, 25 parts Almei- 
dina gum, 5 parts raw rubber, 6 parts sulphur, and 4 parts oleum 
succini. 

Solicum. — A substitute or rather a compound patented by 
a chemist in Copenhagen. The basis of the discovery is waste 
rubber and oil. 

Sulo. — A sulphur oil substitute manufactured in the United 
States. 

Tabbyite. — A mineral product from Utah which seems to 
be a mixture of asphalt and paraffin oils. It is easily manipu- 
lated and quite elastic. 



TEXTILOID—TREMENOL 137 

Textiloid. — A mixture of a resinoline (as described by 
Cadoret under that heading) with natural resins, cellulose, nitro- 
cellulose, or organic substances of animal origin. The resultant 
material may be transparent, white, or colored. It is practically 
uninflammable, has no smell, is very elastic, and, if submitted 
to heat, softens, and can be easily drawn out into fine threads. 
It can be used for waterproofing and in various other ways is 
a good substitute for india rubber. It is flexible and elastic. 
Textiloid is made of 4 parts resinoline, 2 parts nitro-cellulose, 
and 1 part camphor dissolved in alcohol at 90 degrees F. The 
result thus formed may be made in colors by the addition of 
metallic oxides. 

Theskelon Cement. — A metallic substance used for water- 
proofing and for certain kinds of packings. It will neither ex- 
pand, contract, nor rust. It is used instead of wax for sealing 
purposes, and resists acids, alkalies, and grease. It is often used 
in place of asphaltum. It can be mixed with tar, pitch, asphal- 
tum, and other similar ingredients, the compound possessing ex- 
traordinary adhesive power. Patented by Thomas Smith, Lon- 
don. 

Tong Oil Substitutes. — Manufactured from the Chinese 
oil known as tong oil, or wood oil. The oil is heated without 
any foreign matter being added to it, at a temperature of 250 
degrees C, when it becomes solidified. It is then pulverized, 
and impregnated with petroleum, which swells it, and renders 
it more easily worked. Patented by Dr. Charpes Repin, Paris. 

Tremenol. — A German invention that has reference to the 
production of sulphonic acids, sulphones, oils, resin oils, min- 
eral waxes, etc. Results from a treatment of mineral matter 
with fuming sulphuric acids at ordinary temperatures, or with 
concentrated sulphuric acid at 120 degrees C. The invention 
further calls for the treating similarly of the bodies obtained 
from the oil in their precipitation by means of sulphuric acid. 
The products are then washed in brine and water. The inventors 
precipitate glue and gelatine from a slightly acid solution as 
elastic rubber-like substances that can be drawn into threads 
with perfect ease. 

Turnbuli/s Anti-fouling Rubber Paint. — Pitch and resin 
are melted together and then a mixture consisting of crude 



138 SUBSTITUTES FOR RUBBER 

naphtha, dissolved Para rubber, and sifted whiting is added 
thereto. 

Turpentine Rubber. — Manufactured by passing spirits of 
turpentine through a heated tube so as to vaporize it, and mix- 
ing the vapor with hydrochloric or other acid, so as to condense 
and solidify all of the vapor. Patented by A. F. St. George, 
England. 

Unvulcanized Packing Washers. — Goldstein claims in an 
English patent a washer material for the sheet-metal lids of 
vessels is made, without containing sulphur, of a mixture of crude 
rubber, talc, asbestos, and gutta-percha. 

Velvril. — Basis, a drying or semi-drying oil; treated with 
strong nitric acid. This is compounded with nitrocellulose. By 
varying the proportions any consistency may be obtained from 
that of vulcanite to a soft, elastic, rubber-like substance. The 
product is nearly colorless in thin layers, which shows an elas- 
ticity of about 25 per cent, but no greater resilience. Invented 
by W. F. Reid, of England. 

Volenite. — A substitute for india rubber and gutta-percha 
invented by Frederick Lamplough, United States. The com- 
pound is said to be a mixture of resins, or resin oil conveyed 
into a mass of fibrous material by a suitable non-oxidizable 
oil. This latter oil is used simply as a vehicle to carry the resin 
to its place, the process being completed by the distillation of 
the non-oxidizable oil, and the oxidizing of the rest of the mass. 
The oil used is preferably a fish oil, which is refined carefully 
before use. After saturation and treatment the vegetable fiber 
is changed into a homogeneous mass which has many of the 
characteristics of vulcanite. A formula that is said to have 
worked well is 10 parts by weight of fiber, 5 parts resin oil, and 
2 parts fish oil, treated at a temperature of 130 degrees C., for 
say Ay 2 hours. 

Volt ax. — An American insulating compound not subject 
to chemical change, and proof against water, acids, and alkalies. 
Is cheaper than rubber and does not affect copper— hence tinning 
of the wires is not necessary. 

Voltit. — The base of this is glue or gelatine prepared from 
scraps of kid skins, which are treated until they reach a gela- 



VORITE—WOLFERT 139 

tinous mass, which is filtered and mixed with oleic acid, the 
proportion being 80 parts of oleic acid to 20 parts of the gela- 
tine. The mixture is boiled for y 2 hour, and then 11 parts of 
caustic potash solution (in 50 parts of water) are added. The 
boiling is then continued for an hour, and a special mass is 
formed to which are added resin oil, oxidized linseed oil, and 
paraffin. The whole mixture is then boiled 4 to 5 hours. Also 
spelled voltite. It is of French origin. 

Vorite. — A solid blown oil substitute containing no sul- 
phur and no acid or free oil. The melting point for the soft 
grade is from 300 degrees to 400 degrees F., and for the harder 
grade 550 degrees F. It is a floating substitute and burns with- 
out leaving any ash. It is made in three grades, which are dis- 
tinguished by the names soft, ground, and white. According 
to the makers it absolutely resists oxidation and drying out, 
and is already largely used in the manufacture of insulated wire 
and in general mechanical rubber goods. 

Vulcanina. — A preparation of rubber, a Brazilian inven- 
tion, for paving. 

Vulcanine. — A mixture of india rubber, asbestos, litharge, 
lime, and powdered zinc, to which is added a percentage of 
sulphur. Mentioned in a patent granted to J. E. Hopkinson, 
West Drayton, England. 

Waterproof Glue. — A substitute for canvas proofing made 
as follows : Dissolve 16 ounces of glue in 3 pints of skim milk, 
and to increase its strength add a little powdered lime. 

Whaleite. — See Woodite. 

Wheat Rubber. — See Cereal Rubber. 

Wichmann's Substitute. — A combination of vegetable 
albumen and animal casein. 

Winthrop Gum. — Another name for rubberaid. 

Wolfert. — A substitute for rubber made of felt impreg- 
nated with a waterproof substance, presumably vulcanized oil. 
An English invention. 

Woodite. — A name suggested by Sir E. J. Reed for an 
india rubber compound invented by Mrs. A. M. Wood. It is 
said to possess the elasticity of india rubber, to be uninflam- 



140 SUBSTITUTES FOR RUBBER 

mable, and not injured by salt water. It is used in making 
valves, packings, etc. It is claimed that it will not become 
sticky or soft under heat or steam pressure, and will stand hot 
grease and other lubricants, and neither acids, alkalies, nor 
wastes from oil refineries, distilleries, etc., affect it in the least. 
A compound for woodite or whaleite packing is: asbestos fiber 
38 pounds, asbestos powder 38 pounds, earth wax 6 pounds, 
charcoal finely ground 9 pounds, ground whalebone 20 pounds, 
Para rubber 80 pounds, and sulphur 5 pounds. 

Zackingummi. — Substitute invented by Zachias Olsson, a 
Swedish chemist. Consists of a mixture of glycerine, chloride 
of calcium, magnesium, and paraffin. 

Zinsser's Barrel Lining. — A compound for lining casks, 
consisting of deodorized copal, rosin, india rubber, and a non- 
drying fat, with coloring matter, such as asphalt. 



CHAPTER VIII. 

SUBSTITUTES FOR HARD RUBBER AND GUTTA- 
PERCHA, INCLUDING CELLULOSE 
PRODUCTS. 

Hard Rubber in its best estate is so valuable and perfect 
a product that it would always have the preference were it not 
for its unavoidable high cost. Because of this cost there are 
many substitutes for it that counterfeit it in texture, color, and 
quality, but are never quite its equal in all these points of ex- 
cellence. These substitutes are made of cellulose, gums, and 
animal, vegetable, and earthy matters, having a variety of dis- 
tinctive names and varied uses. To the popular mind, if they 
look like ebonite, they are hard rubber. In the same way, gutta- 
percha is often confounded with hard rubber; which it resem- 
bles under many conditions. The following list covers not only 
certain widely known compounds of hard rubber and gutta- 
percha, but a number of substitutes for them are now put to 
many uses, the chief of which, perhaps, is insulation. 

Alexite. — An American insulating material which can be 
molded in any shape, is waterproof, fireproof, and acid proof, 
and can be produced in any color. In texture and general ap- 
pearance it resembles vulcanite. 

Ambroin. — A German substitute for hard rubber, consist- 
ing of fiber, silica, and resin compressed to a mass. Its color 
varies from light brown to green or black. Nitric and acetic 
acids do not affect it, and even aqua regia does not injure it. 
Under a moderate heat it softens slightly and can be worked, 
like vulcanite, in a mold. It also takes a bright finish from the 
buffing wheel. 

Armalac. — See Insulac. 

Artificial Whalebone. — A well-known product made as 
follows : india rubber 20 parts, sulphur 5 parts, shellac 4 parts, 
magnesia 4 parts, and gold brimstone 5 parts. Vulcanized some- 
what the same as hard rubber. 

141 



142 SUBSTITUTES FOR HARD RUBBER 

Bakelite. — A patented substance said to have the com- 
bined properties of amber, celluloid, and hard rubber. The 
invention of Dr. L. E. Baekeland. It is a compound of or con- 
densation product of formaldehyde and phenol or carbolic acid. 
It has long been known to chemists that formaldehyde and phenol 
formed condensation products which have been put on the mar- 
ket as artificial gums and resins and used to some extent. It 
was further known that by a certain process this material was 
condensed into a hard, resinous body which resisted every known 
chemical solvent and was only changed by actual burning. This 
substance was usually porous and was of no value. Dr. 
Baekeland discovered that, by carrying on the process in a 
vulcanizer where heat and temperature conditions could be con- 
trolled, the reaction could be divided into several stages, pro- 
ducing first a plastic mass which can be molded or carved, and 
on further treatment in the vulcanizer where it is submitted with 
certain chemicals to carefully regulated conditions of heat and 
pressure, that a hard, transparent substance could be produced 
which is most inert chemically. Bakelite resembles physically 
and possibly chemically the Chinese or Japanese lacquer. It is 
manufactured into a large variety of electrical goods such as 
terminals, high potential insulators and, in its liquid form, is 
used to impregnate armature and other coils, the impregnated 
material being subsequently converted by heat into the hard 
form. 

Bakelite take's a high polish and machines freely. It is well 
adapted to manufacture in rubber works, as most of the ma- 
chinery can be used with little change. 

Balenite, as the name signifies, is intended as a substitute 
for whalebone. It is quite elastic; in other words, it is neither 
hard nor soft, but may be characterized as semi-hard. A well- 
known compound for this is india rubber 100 parts, shellac 20 
parts, burned magnesia 20 parts, sulphur 25 parts, and orpiment 
20 parts. ( Hotter. ) 

Betite. — An English insulating material which is said to 
be bitumen refined to absolute purity and vulcanized. It is 
used on cables, in underground work, for low pressure resis- 
tance, and in rare instances for high pressure. 



BROOKS ITE— CELLULOID 143 

Brooksite. — A compound of resin and heavy resin oils for 
insulating- purposes. 

Brown's Substitute for Hard Rubber. — Made of bitu- 
men sulphur, lead peroxide, and gum camphor. Amalgamated 
by heat. 

Caoutchouc Aluta. — A composition used as a substitute 
for hard rubber, made of leather scraps boiled in water, with 
a sufficient quantity of oxalic acid to dissolve them, and a por- 
tion of glue. To this are added resin, pitch, beeswax, and copal 
gum, dissolved in oil. India rubber boiled in linseed oil is then 
added and a powder formed of plaster of Paris, and a coloring 
matter is stirred into the composition to thicken and stiffen it. 

Carbo-nite. — A cottonseed oil preparation intended as a 
substitute for hard rubber. 

Cellit. — A cellulose acetate. The invention of a German 
chemist, designed to take the place of celluloid, but to be more 
easily worked and safer by varying the organic substance that 
takes the place of camphor. A great variety of products is pro- 
duced. The substance varies from a soft plastic to a hard 
product according to the degree of compound used. 

Cellulith. — A cellulose substitute said to be an improve- 
ment on viscoid. Mixes readily with shellac, rubber, etc. 

Celluloid is made in the main from camphor and nitro- 
cellulose in alcohol, ether being sometimes employed as an ad- 
ditional solvent. The paste formed in this way is warmed 
gently, and then rolled out into thin sheets. The product is a 
brittle, horny mass, consisting of a chemical, or at least an inti- 
mate, mixture of camphor and pyroxylin. Ordinarily it is 
highly inflammable. A great variety of coloring matters may 
be added to it and it is susceptible to manipulation and processes 
whereby it has been made quite flexible and practically incom- 
bustible. Crude celluloid has a specific gravity varying between 
1.25 and 1.45, and has a strong odor of camphor. 

Cellulose is a pure substance forming the cellular tissue of 
plants. Specific gravity 1.53. In the arts use is made generally 
of cotton or filter paper which has been treated with acids to 
dissolve out impurities, and forms a basis for the manufacture 



144 SUBSTITUTES FOR HARD RUBBER 

of celluloid, gun cotton, pyroxylin, and xylonite. On analysis 
it shows: carbon 44.44, hydrogen 6.18, oxygen 49.38. It is dis- 
solved in sulphuric acid, and is converted into dextrine, and, by 
prolonging the action, into glucose. So far it has not been used 
largely in rubber compounding, but both alone and in connection 
with various other ingredients has been applied as a waterproof- 
ing. It is the basis of certain Swiss puncture fluids. 

Ce-re-gum. — A compound made by a secret process, and 
which, vulcanized, produces a fairly good imitation of hard 
rubber. Invention of H. W. Morgan, United States. 

Chatter-ton's Compound. — A widely known compound 
sold the world over for connections for joint sheets and for 
uniting gutta-percha parts, and also for cementing gutta-percha 
to wood. It softens readily at 100 degrees F., and becomes firm 
again when cold. Its specific gravity is about 1.02. The best 
compound is 1 part by weight of Stockholm tar, 1 part resin, 
and 3 parts cleansed gutta-percha, melted and mixed. 

Condensite is a phenolic condensation product invented by 
J. W. Aylsworth, who for more than a quarter of a century was 
associated with Thomas A. Edison, as his chief consulting 
chemist. 

Condensite was developed in the course of a search for a 
better material to be used in the manufacture of phonograph 
records. It is the only phenolic condensation product that has 
ever been successfully used in the making of a record, which is 
probably the most difficult plastic molded article to manufacture 
without imperfections. 

Condensite is unlike any other phenolic condensation prod- 
uct, because of the unique method by which it is made. By 
this process the product, during the reaction between the chemi- 
cals of which it is composed, is heated to such a degree as to 
dissociate all the water. 

The absence of water, even in minute quantities, gives to 
the final product, a capacity for taking extremely minute im- 
pressions in molding, as well as imparting to them unusual 
electrical and other qualities of value. 

The next step in the manufacture of condensite very much 
resembles that of rubber manufacture. It is compounded with 



CONDENSITE—ELECTROSE 145 

a chemical that reacts upon it when heated, and hardens the 
product, just as sulphur or other vulcanizing mediums harden 
rubber when similarly treated, and the process of molding is 
very much the same as in rubber manufacture. 

Condensite has in some instances been used in the place of 
rubber, but its development has chiefly been in competition with 
other substances, and with respect to rubber rather supplements 
than serves as a substitute for it. Each possesses valuable prop- 
erties not found in the other. 

Coralite. — A name for vulcanite which is colored to imitate 
coral. 

Corimite is a solid substance derived from fish offal through 
a process recently invented by a Danish chemist, and said to be 
particularly suitable for electric insulation. 

Cornite. — A specially hard vulcanite or hard rubber, so 
named from the Latin cornu (a horn). 

De Pont Substitutes. — An English patented product made 
from asbestos 30 parts, plaster of Paris 5 parts, clay 8 parts, 
copal 15 parts, tar 5 parts, bitumen 15 parts, aniline 2 parts, 
lampblack 15 parts, mica 4 parts, wax 3 parts. 

Diatite. — A combination of diatomaceous earth, and shellac, 
made under very heavy pressure. It may be made of any color, 
and is used as a substitute for hard rubber. 

Ebonitine. — A hard rubber substitute formerly used for 
phonograph records. Is of a brilliant black color. Said to be 
a good insulator and resists acids. Of German origin. 

Electrose. — A substitute for hard rubber for which the fol- 
lowing advantages are claimed: It will not tarnish metal, as 
no sulphur is used in its vulcanization; it is cheaper than hard 
rubber; it possesses high insulation properties; it can be melted 
readily into any shape, or made of any color; it does not fade; 
it possesses great strength, and takes a high polish; changes of 
temperature do not affect it ; and it withstands the weaker acids 
and alkalies. 

Esbenite. — Made of pure cellulose, chemically incorpo- 
rated with mica in the form of fine powder, with the addition 
of magnesia and a silicate, thus forming strong and close grained 
artificial mica. It is flexible, and can be molded into any shape. 



146 SUBSTITUTES FOR HARD RUBBER 

Esbenite is waterproof, does not burn readily, and is thoroughly 
airproof. Manufactured in England. 

Fibrone. — A substitute for hard rubber which is a good 
non-conductor, waterproof, and can be handled in a lathe like 
vulcanite. It is said to be durable, does not contract or ex- 
pand, and is made in all colors. It is used for thumbscrews, 
pushbuttons, etc. Plasticon is similar to fibrone, but heavier 
and of a more stony nature, and probably made of the same 
material. 

Galalith. — A German product from casein. The process 
roughly is to make the casein insoluble by the addition of salts 
and acids. The product is then dehydrated and dried, when, by 
the addition of formaldehyde, galalith is obtained. The process 
is protected by numerous patents. 

Gun Cotton. — Prepared by treating cotton wool with a 
mixture of strong sulphuric and nitric acids, or nitrate of pot- 
ash may be substituted for nitric acid. After treatment with 
acid the gun cotton is rinsed carefully in cold running water, 
and then dried by pressure or by exposure to the air. All acid 
should be removed to prevent danger of explosion. Gun cotton 
has been used to render fabrics waterproof, for varnishing india 
rubber to render it impervious to gases, and in insulation work. 
Alexander Parkes, as far back as 1855, used a solution of gun 
cotton with gums or resins to take the place of compounds of 
india rubber. He rendered gun cotton less inflammable by using 
biphosphate of ammonia, magnesia, talc, alum, or similar sub- 
stances. As a good solvent for gun cotton, he distilled in 1 
gallon of naphtha from 2 to 6 pounds of chloride of calcium. 
Charles Macintosh used as a solvent equal parts of wood spirit 
and coal tar naphtha. 

Hard Core for Golf Balls. — An English composition 
which consists of 100 parts calcium chloride, 25 parts chloride 
of zinc, 100 parts potato starch. 

Hyaline. — Made of a mixture of equal parts of gun cot- 
ton and a variety of resins. The gun cotton is dissolved in 
ether and the resins in solution are added, the result being a 
thick, gelatinous mass. When allowed to dry, this mass soon 



INSOLACIT—KERATOL 147 

hardens and forms a horny, incombustible material. Invented 
by Frederick Eckstein, Vienna. 

Insolacit. — An insulating material produced either as a 
liquid, semi-liquid, or solid. It is not inflammable or affected 
by corrosive acids, alkalies, saline substances, etc. It is a German 
product and the compound remains a secret. 

Insulate. — A molding hard composition for electrical in- 
sulations, resembling other condensation products. 

Insullac. — A spirit copal resin varnish, with the acids of 
the resins neutralized as much as possible, to prevent the resin 
acids from attacking the copper wire. It is a transparent elastic 
material, and is superior to shellac. Armalac is made of black 
paraffin wax, in solution in petroleum. It remains permanently 
plastic under heat, although it dries quickly and thoroughly. 
Manufactured in the United States. 

Isolatinb. — An American insulating material prepared 
especially for high resistance. It is said to be flexible, not to 
be affected by cold or heat unless the latter is artificial, and to 
be durable. It is also said to protect metal. 

Kasenoid. — An English substitute for ebonite, galalith and 
zylonite for many purposes. The properties are quite similar to 
those of galalith — it is tough, resilient, non-inflammable, a good 
insulator, capable of being molded, and is made in a variety of 
colors, either as sheet or rod. It can be turned and polished and 
takes an excellent thread. 

Kempeff Hard Rubber Substitute. — A mixture consist- 
ing of 20 per cent, resin and asphaltum, 15 per cent, china clay, 
11 per cent, kieselguhr. Mixture is allowed to cool; ground 
dry; with 4 per cent, of sulphur, and 50 per cent, of ground 
asbestos fiber. It is elastic and unaffected by acids. 

Keratite. — Another name for hard rubber, derived from 
the Greek word meaning horn. 

Keratol. — An American waterproof preparation, not of 
the nature of rubber, but probably one of the cellulose sub- 
stitutes. It is a colorless transparent substance, and when ap- 
plied to fabrics renders them waterproof and prevents crocking 
and fading. It also strengthens the fabric, and allows stains 



148 SUBSTITUTES FOR HARD RUBBER 

to be washed off. An artificial leather is also made of Keratol. 
The name is adapted from the Greek word keros, meaning 
hornlike. 

Kiel Compounds. — One of these well-known compositions 
consists of india rubber, sulphur, pumice stone, oil, and bees- 
wax. The product is a hard rubber, said to possess a superior 
elasticity and toughness, and capable of being vulcanized in sheets 
at least 2^ inches thick. This compound is not affected by the 
most intense cold, and will stand a higher temperature than 
ordinary rubber. It also burns with difficulty. Its ingredients 
are said to mix faster and more uniformly than those of other 
compounds. It resists acids, and other corrosive substances, is a 
perfect insulating material, and is cheap. Another Kiel com- 
pound is made of india rubber, sulphur, and mineral oil. It is 
more flexible than ordinary hard rubber, and when warm is 
more plastic than such compounds. It is also less brittle and 
cheaper, and can be turned in a lathe with greater facility and 
less injury to the tools. 

Kornite. — A Russian substitute for hard rubber made at 
Riga. It consists of 25 per cent, of prepared fish bone and 75 
per cent, of scrap horn ground to dust, and then melted under 
high pressure and steam heat. 

Lactitis. — An artificial ivory made from milk, the process 
being coagulation, straining, and rejection of the whey. Ten 
pounds of the curd are then taken and mixed with the solution 
of 3 pounds of borax in 3 quarts of water. The mixture is then 
placed in a vessel over slow fire and left until it separates into 
two parts, one as thin as water, the other resembling melted 
gelatine. The watery part is drawn off, and to the residue is 
added a solution of 1 pound of mineral salt in 3 pints of water. 
(Sugar of lead answers very well as the mineral salt.) This 
brings about another separation of the mass, into a liquid and 
a mushy. solid. The liquid is strained or filtered off, and at this 
point coloring matter may be added. The solid is now subjected 
to heavy pressure in molds of any shape, and afterwards dried 
under great heat. The resulting product may be used in the 
manufacture of billiard balls, knife handles, or anything for 
which ebonite or celluloid is adapted. 



LAMINA FIBER— PEGAMOID 149 

Lamina Fiber. — An American invention, used chiefly for 
electrical purposes. It is of various colors, heavier than vul- 
canized rubber, and swells to nearly double its weight when 
placed in water. It is probably a cellulose compound containing 
no rubber. 

Leatheroid. — A mixture of American origin, made in black, 
red and gray, and similar to vulcanized fiber. It is insoluble in 
ordinary solvents, uninjured by alcohol, ether, ammonia, tur- 
pentine, naphtha, or other oils ; is very tough, a good insulator, 
and of low cost. 

Marloid. — An insulating material said to be made from the 
hides of certain animals, treated by a chemical process, making 
it so hard that it can be handled in every way the same as ebon- 
ite. It may be transparent or opaque, and is capable of receiv- 
ing a very high polish. It is said to give an insulation of 2,000 
megohms, is uninflammable, and of English origin. 

Micanite. — Mica cemented together under pressure with an 
india rubber compound. Manufactured in America. 

Nigrite. — An insulating compound consisting of a mixture 
of india rubber and ozocerite. 

Nitrocellulose. — This is produced by the action upon cel- 
lulose of nitric acid or a mixture of nitric and sulphuric acids. 
According to the length of time the acid is allowed to act, the 
resulting nitrocellulose contains 53.7, 43.6, 36.7 or 28 per cent. 
of nitric acid (nitric-anhydride). Gun cotton is usually a mix- 
ture containing higher percentages, while pyroxylin — or, as it 
is sometimes called, soluble cotton — is a mixture of lower com- 
pounds. The solution of pyroxylin in a mixture of alcohol and 
ether is called collodion. 

Pantasote. — A cellulose product largely used in the manu- 
facture of artificial leathers. 

Pegamoid. — This, although covered by several patents, is 
said also to involve certain secret processes. In a general way, 
however, the substance is prepared by treating a fine grade of 
cellulose with a mixture of sulphuric or nitric acid to form nitro- 
cellulose or gun cotton, which is then dissolved in a suitable 
alcohol. The pegamoid patents call for the addition of glycerine, 
sweet or olive oil, and various coloring matters. 



150 SUBSTITUTES FOR HARD RUBBER 

Plasticon. — See Fibrone. 

Plastite. — A vulcanite which is made extra hard and is 
not possessed of any special amount of elasticity. The stock 
recipe for this is : india rubber 100 parts, sulphur 25 parts, mag- 
nesia 50 parts, orpiment 50 parts, coal tar asphaltum 60 parts. 
It is very hard and solid, and takes a high degree of smooth- 
ness and polish. (Hoffer.) 

Potato Celluloid. — An Austrian invention relating to an 
artificial solid produced from potatoes boiled 36 hours in a fluid 
containing 8 parts of sulphuric acid and 100 parts of water, 
and then dried. Pipe bowls made from it for the French market 
are said to be hardly distinguishable from leal meerschaum. 
Billiard balls are also said to be made from it. 

Presspahm. — An English insulating material made from 
wood fiber so treated that it can be run through rolls into sheets 
of varying thicknesses. It is said to be capable of withstanding 
high temperatures, and is used not only in connection with elec- 
trical machinery, but also for bookbinding and for putting a 
finish on cloth. 

Pyroxylin. — A species of gun cotton less explosive in its 
qualities, prepared from cellulose by means of nitro-sulphuric 
acid. Its solution in a mixture of ether and alcohol is called 
collodion. 

Siluminite. — This new insulating material, of English ori- 
gin, is a hard black substance, ringing like slate, but of far 
greater strength; it can be sawed, filed, drilled, tapped, turned, 
and polished with ease, and can be molded to any shape in the 
course of manufacture but not afterwards. It is not softened 
by heat (it is subject to a temperature of more than 600 de- 
grees F. at the makers' works) and is not brittle. Immersion 
in oil or caustic alkali, or boiling water, leaves it unchanged, 
and it is non-hygroscopic. It possesses high dielectric strength, 
this being between 10,000 and 13,000 volts per millimeter. Its 
structure is homogeneous and dense, the weight of a square foot 
%-inch thick, being 2.4 pounds. Metal parts can be insulated 
by compressing siluminite on them in any desired shape, thus 
avoiding the cementing or screwing process now necessary in 
most cases. The substances with which it will most directly 



S OREL'S COMPOUND— VITRITE 151 

compete are porcelain, glass, mica, fiber, ebonite, wood, slate, 
marble and molded compounds. It is supplied in the form of 
rods, sheets, tubes and various molded specialties. 

Sorei/s Compound. — A so-called substitute for gutta- 
percha consisting of 2 parts resin, 2 parts asphaltum, 8 parts 
resin oil, 6 parts slaked lime, 3 parts water, 10 parts potter's 
clay, and 12 parts gutta-percha. Five per cent, of stearic acid 
is sometimes added. 

Stabilit. — A German invention, the compound for which 
is a secret, designed to be half way between hard rubber and 
vulcanized fiber. It is not affected by corroding substances, and 
does not absorb moisture. It withstands boiling water where 
hard rubber and vulcanized fiber do not, and is not attacked by 
muriatic acid or sulphuric acid. 

Texoderm. — An imitation leather with a hard, durable 
waterproof surface. Basis of which is cellulose. 

Vegetaline. — Cellulose treated with sulphuric acid, dried 
and ground, then treated with resinate of soda. 

Viscoid. — A compound of viscose, formed by mixing with 
it hot bituminous matter such as tar, pitch dissolved in coal tar, 
or the like. The resultant mixture, when solidified, constitutes 
a material of a high insulating character, and is produced at a 
low cost. The bituminous and cellulose matter may be mixed 
in equal proportions, although there is a wide range of com- 
pounds that may be made through the use of various propor- 
tions of the substances. 

Viscose. — An English cellulose product, used as a substitute 
for vulcanite. It may be of any color or any degree of hard- 
ness. It has been used in connection with rubber, experimen- 
tally, with excellent results. As a friction for belting it is said 
to be excellent, whether or not the belt has the regulation rubber 
cover. 

Vitrite. — A jet black, perfectly hard material, having a 
smooth polished appearance similar to ebonite. It is not affected 
by dampness or acids. It is a good insulator, is of low cost, 
and easily worked. 



152 SUBSTITUTES FOR HARD RUBBER 

Vulcabeston. — A composition of asbestos and india rubber, 
forming a product which is a non-conductor of electricity and 
stands the severest tests, resisting heat wonderfully. Invented 
by R. N. Pratt, United States. 

Vulcanized Fiber. — This material, which is very largely 
used, is made of cotton paper pulp, chemically dissolved, and 
solidified under enormous pressure. It is unattacked by ordi- 
nary solvents such as alcohol, turpentine, ammonia, etc. It ap- 
pears on the market in two forms — hard and flexible. The hard 
fiber resembles horn and is exceedingly tough and strong, while 
the flexible fiber has the appearance of a very close-grained 
leather. It is an insulator in dry places, but, as it will absorb 
moisture, it is useless in places requiring waterproof qualities. 
It is made in three colors — black, red, and gray. Vulcanized 
fiber is unaffected by oils or fats, and will stand action of hot 
grease. Low grades have been found adulterated with chloride 
of zinc and calcium, to the extent of nearly 50 per cent, of its 
weight. 

Weber's Cellulose Compound. — Ten pounds of cellulose 
steeped in a 20 per cent, solution of caustic soda and allowed 
to stand for ten hours ; then pressed until its weight is 35 pounds ; 
then treated with 8 pounds cold carbon bisulphide for three 
hours ; then emulsified with a mixture of 40 pounds Pontianak 
gum, 15 pounds mineral oil, and 10 pounds stearine pitch. 

Willoughby Smith's Gutta-percha. — Gutta-percha re- 
fined by a special process invented by Willoughby Smith. Valued 
in England as giving an increased speed over electrical conduc- 
tors insulated with it. 

Wray's Compound. — A composition of india rubber, silica, 
powdered alum, and gutta-percha. Used in climates too hot for 
gutta-percha by itself. It is easily attacked by seawater. 

Xelton. — A substitute for hard rubber manufactured prin- 
cipally for use in making battery jars. It originated in Philadel- 
phia. 

Xylonite. — See Celluloid. 



CHAPTER IX. 

RESINS, BALSAMS, GUMS, EARTH WAXES, AND 

GUM-LIKE SUBSTANCES USED IN 

RUBBER COMPOUNDING. 

A great variety of vegetable, mineral, and animal resins 
and waxes find uses in admixture with india rubber and gutta- 
percha. Their important uses are to render compounds ad- 
hesive, as in frictions, to assist in insulation, to add luster, and 
to modify the texture of the vulcanized compound. Many 
gums, like many earths, -lend special virtues which they pos- 
sess to rubber compounds. The more important of these ma- 
terials, and those most generally used, are described in the fol- 
lowing pages. 

Acacia. — See Arabic, gum. 

Acroides Gum, also known as Botany Bay gum or mineral 
lac, is the name given to the resins of the various branches of 
the Xanthorrhcea plant species. 

Red gum acroides comes from the Xanthorrhcea Australis 
and Arborea. It forms flat pieces from one-half to one and one- 
half inches thick, sometimes as big as the hand, shows distinct 
traces of its structure and embraces unresinified tissues. It is 
reddish-brown in color, leaves an orange-red mark, smells some- 
what like benzoin, and has an unpleasant taste like cinnamon. 

Yellow gum acroides comes from the Xanthorrhcea Hastilis, 
forms round or oval pieces of various sizes, resembles gamboge 
on a fresh fracture, becomes covered with reddish-brown coat- 
ing on exposure to the air, smells like benzoin, has a somewhat 
sweet or spicy taste, and contains in addition regular admixtures. 

Both gums are soluble in acids and ether. They contain 
paracoumaric acid, benzoic acid, para-oxy-benzin-aldehyde and 
abietic acid, the yellow gum having also traces of cinnamic acid 
and styracin. They are used in the manufacture of sealing wax 
and colored varnishes which do not fade on exposure to the 

153 



154 GUMS AND BALSAMS 

light and which are suitable for painting the glasses of photo- 
graphic dark-room lamps. They are also employed in making 
the better classes of soap ; in the preparation of picric acid and 
paracoumaric acid, as well as in the linenizing of the thinner 
qualities of paper. For insulating purposes acroides is melted 
and mixed with other ingredients and molded to form insulat- 
ing pieces for electrical apparatus. The exact process is a manu- 
facturing secret. 

Acroides was used in England in the eighteenth century as 
a medicine for the stomach, but it was not employed for manu- 
facturing purposes until 1840 in England and 1860 on the Con- 
tinent. 

Adamanta Resin. — An imitation copal, manufactured from 
common resin by a special hardening process. It is not soluble 
in alcohol or benzine, but completely so in boiling turpentine. 
It is free from acids and alkalies, and has the same melting point 
as Zanzibar copal. It is used rarely in rubber shoe varnish, 
and often in cheap frictions in mechanical lines, being moistened 
with resin oil to increase its adhesiveness. 

Amber. — A fossil resin chiefly found in Prussia, on the 
shores of the Baltic sea; it occurs also in Sicily and sometimes 
in the United States. It is the hardest and heaviest of the resins. 
Its specific gravity is about 1.07. By distillation a yellow oil — 
oleum succini or oil of amber — is obtained, and a yellow resin 
remains in the still. Amber varies in color from light yellow to 
a deep brownish-red. It is insoluble in almost all of the ordinary 
solvents. When heated above its melting point, however, it 
becomes partly decomposed, and is then soluble in oil of tur- 
pentine and alcohol. It makes a very fine transparent varnish, 
which is used on negatives in photographing. It is used in 
cements for fastening linoleum and rubber tiling to decks, and 
is also mentioned in the formulas for certain patented gums. 

Ammoniacum Gum. — Exclusively obtained from Persia as 
tears, or aggregated masses, of a peculiar smell and a taste 
slightly sweetish, bitter, and somewhat acrid. Its specific grav- 
ity is 1.207. Used in solutions for pressed leather cuttings and 
fibrous wastes. Ten parts of this gum mixed with 20 or 25 



AN I ME— ASPHALT 155 

parts of gutta-percha form a cement possessing both elasticity 
and solidity, and is thoroughly waterproof; used for filling 
cracks in horses' hoofs. Also used with gutta-percha, boiled 
linseed oil, and dry casein or caseum, for sticking together small 
particles of any dry matter in the production of artificial leather. 

Anime is a South American fossil resin similar to copal. 
It occurs in small, irregular pieces of a pale yellow color. Has 
a high melting point, and its specific gravity is 1.028 to 1.072. 
Mixed with rubber and earthy matters and dissolved in tur- 
pentine, it formed one of the early compounds for clothing. 

Arabic Gum is exuded from a species of Acacia. It is 
made up of clear or semi-transparent fragments, hard and brit- 
tle, breaking with shining fracture. It is inodorous and feebly 
sweetish to the taste. Its specific gravity is 1.31 to 1.52, for 
dried gum. It comes from Africa and is known also as acacia 
and gum Senegal. It dissolves in hot or cold water. It is used 
in connection with plaster of Paris in making a tougher surface 
mold for small and experimental rubber work. Enough gum 
is added to make the mixing solution about the thickness of a 
thin syrup. It is largely' used in cements. It is also used in 
certain shower-proof compounds and in paste blackings made of 
caoutchouc oil, vinegar, molasses, and boneblack. 

Arkosite. — An infusible pure asphaltite. It is a valuable 
pigment for structural paint and in rubber goods. 

Asphalt is undoubtedly an oxidized residue from evapor- 
ated petroleum. Its specific gravity varies from 1.00 to 1.68. 
This name is applied usually to the solid bitumen, the liquid 
being called mineral tar, and sometimes maltha. It is chiefly 
made up of hydrocarbons, but contains a certain amount of 
sulphur and nitrogenous bodies. It is known also as natural 
pitch, Jews' pitch, asphaltum, bitumen, etc. It is a black, hard 
substance which, when freshly broken, shows shining surfaces 
that are always correspondingly rounding and hollowing. It is 
insoluble in water and alcohol, but dissolves in benzine, acetone, 
and carbon disulphide. Is used in rubber compounding in place 
of coal tar, and in insulating compositions, and in certain sub- 
stitutes like kerite. Commercially there are two grades, known 



156 GUMS AND BALSAMS 

as "lake pitch" and "land pitch," of which the latter is the 
harder. 

In solution it is used sometimes to protect rubber goods 
that are exposed to the destructive influence of brine:. A little 
asphalt is also said to increase the elasticity of hard rubber. 
Asphalt mixed with resin and oil of tar forms a low-grade arti- 
ficial gutta-percha. It is added to "Cooley's artificial leather" 
to harden it and enable it to resist heat. It is also the basis of 
one type of marine glue. 

Asphalt, Artificial. — This is made by heating sulphur 
and resin together to about 250 degrees C, where the reaction 
takes place, attended by the evolution of sulphuret of hydrogen, 
and leaving an almost black, pitchy substance resembling asphalt. 
It is insoluble in alcohol, but dissolves readily in benzine. 

Balsam. — This term is given to oleo resins which are soft 
at ordinary temperatures, and are really a mixture of such a 
resin and the essential oil of the plant from which they exude, 
such as benzoin, tolu, etc. 

Balsam of Storax (or Styrax). — Produced from the inner 
bark of a tree of the genus Storax, in Asia Minor. Commer- 
cially it is a soft, coarse, dark-colored powder; or, more com- 
monly, a semi-fluid, adhesive substance, brown outside, greenish- 
gray inside. The sweet gum of the southern United States is 
allied to the Eastern drug, and was formerly much used in 
chewing gum. Used in general cements, being particularly good 
in leather cements; also for glass, stone, and earthenware 
cements. 

Balsam of Sulphur. — A solution of sulphur in boiling 
volatile or olive oil. Used in certain rubber compounds as a 
vulcanizing agent and a protection against blooming. 

Beeswax is obtained from the comb built by honey bees. 
The crude wax is yellow and soft, with a granular fracture. Its 
specific gravity varies between .965 and .969, its melting point 
being between 140 degrees and 144 degrees F. It is often adul- 
terated by water, by white mineral powders, and by cheaper sub- 
stances, such as vegetable wax, paraffin, etc. White wax is that 
which has been exposed to the sun or to the moderate action of 



BENZOIN— BITUMEN 157 

nitric or chromic acid, thereby being- bleached. It is sometimes 
used with rubber in medicinal plasters. Ordinary beeswax is 
largely used in Kiel's hard-rubber compounds. Sheet beeswax 
is often used in the work of vulcanite pattern making. It is 
also used 'in processes for making fabrics water-repellent, the 
other ingredients being alumina, resin, soap, wax, and silicate 
of soda. With gutta-percha it is an ingredient in shoemakers' 
wax, and also in certain proofing compounds. Hancock used it 
in a gutta-percha compound for a soft effect. In a hard rubber 
compound made up of india rubber, sulphur, oil, and pumice 
stone, it is said to be acid proof. 

Benzoin. — Occurs in lumps of yellowish brown tears, stuck 
together and more or less mottled from the white inside the tears. 
Its specific gravity is from 1.063 to 1.092. Of an agreeable bal- 
samic odor and very little taste, but irritating when chewed for 
some time. Used in linseed oil proofings, presumably to kill 
odor; also in certain gutta-percha and india-rubber compounds 
for disguising the odors. Four per cent, of the weight of the 
mass is said to be sufficient to make the odor an agreeable one. 
According to Forster, a little of it mixed with gutta-percha 
greatly improves the quality. 

Birch-bark Tar. — A peculiar tar obtained during the dis- 
tillation of birch-bark for oil, being probably the same as Rus- 
sian jackten extract. Used in the manufacture of certain rubber 
substitutes. Specific gravity 1.82. 

Bitumen. — The term applied to a body made up of several 
hydrocarbons. It resembles Trinidad asphalt and is of the same 
nature. Its specific gravity is from 1.073 to 1.160. Artificially 
it is prepared from shales, mineral asphalt, etc. It is used as a 
source of paraffin. The West Indian product is known as chap- 
apote. A solution is made from it in which the tapes are soaked 
that are used for covering wire that has been insulated with 
india rubber. Bitumen has been utilized by what is known as 
the calendar process, which is a partial vulcanization, rendering 
it valuable as an insulator. 

Bitumen, Auvergne. — A species of natural asphalt found 
in the province of Auvergne, France. It is similar to Trinidad 
asphalt, but is impure, containing clay, silica, magnesia, iron, and 
traces of arsenic. See Asphalt. 



158 GUMS AND BALSAMS 

Black Pitch. — Is the residue left after the oils of tar have 
been distilled from that body. Used in weather-proofing work. 

British Gum. — See Dextrine^ 

Burgundy Pitch. — Is obtained from the hardened juice or 
sap which concretes upon the bark of the Norway spruce. Spe- 
cific gravity 1.07-1.10. As imported it is often quite impure and 
should be melted and strained before being used. It is almost 
entirely soluble in glacial acetic acid or boiling alcohol, and some- 
what in cold alcohol. When pure it is hard and brittle, with a 
shining fracture, dissolves in benzine, acetone, and carbon disul- 
phide. Is usually reddish or yellowish-brown, aromatic. It is 
much used in cements, in electric tape, and in the manufacture 
of porous plasters. Common resin is often melted and mixed 
with fats and water, forming a gum that much resembles Bur- 
gundy pitch. 

Burmite Amber. — Found in Burma, but quite inferior in 
quality. It is a little harder than amber proper, is easily cut, 
takes an excellent polish, but has less variety of color. See 
Amber. 

Button Lac — See Shellac. 

Camphor. — The white transparent substance known by this 
name is obtained from Japan and the island of Formosa. It is 
really an oxygenated essential oil. Its specific gravity is 0.985. 
Sparingly soluble in water, and very soluble in alcohol, ether, 
acetic acid, and hydrocarbons or volatile oils. Is largely used 
in the manufacture of celluloid. Gum camphor is also used in 
compounds of the substitute order like textiloid, kerite, etc. Was 
also the basis of the heevenoid compounds (which see). 

Canada Balsam. — Sometimes called Canada turpentine. It 
is derived from the Abies balsamea. Specific gravity 0.900- 
0.998. It is a yellowish or greenish transparent liquid, com- 
pletely soluble in ether, chloroform, or benzol. It is sometimes 
called balsam of fir, but it does not really belong to the balsams, 
being a true turpentine. Strasburg turpentine is sometimes sub- 
stituted for it commercially. It is used in certain compounds 
to prevent sulphur from efflorescing. With paraffin, beeswax, 
and coloring matters, it is used for insulating colored yarns that 



CANDELITTA WAX— CASEIN 159 

are used for annunciator and similar wires, and it was also used 
by Duncan in gutta-percha cements for leather. 

Candelitta Wax. — This wax is found coating the surface 
of a plant growing wild in semi-arid northern Mexico and south- 
ern Texas. When refined the wax is opaque, of a brownish 
color. It is intermediate in hardness between beeswax and car- 
nauba wax. Its specific gravity is 0.983. It is used in polishing 
compositions and for raising the melting point of softer waxes. 

Candle Tar. — The residual products from the distillation 
of animal fats, oils, etc., are known as candle tar. This product 
is sometimes soft and ropy, and at other times quite hard. Mixed 
with sulphur, it is said to produce a compound having some of 
the elasticity and other desirable qualities of vulcanized india 
rubber. 

Carnauba Wax or Carn Gum is found in Brazil, where it 
forms as a coating on the leaves of a certain palm (Corypha 
ceriferd), and is removed by pounding and shaking. It is very 
hard and is of a greenish or grayish color. Its specific gravity 
is about 0.995, it is odorless, and melts at 185 degrees F. It dis- 
solves completely in boiling alcohol, and is used on insulated wire 
as a finish, and in the manufacture of wax varnishes. Used in- 
stead of ozocerite as a finish for tape or braids that cover in- 
sulated wire. 

Casein (also called Caseum) is one of the chief constituents 
of milk, being that part which forms the curd of sour milk, and 
is familiar in the form of cheese. Specific gravity 1.26. A 
similar substance, prepared from peas, beans, lentils, and the 
like, is called vegetable casein. It is used in shower-proofing 
after a German formula in connection with soda, lime, and 
acetate of alumina; also, in cements of which gutta-percha is 
the base, for joining small particles of leather, shavings, etc. In 
Kittel's compound, casein dried and powdered is mixed with 
linseed oil. India rubber or gutta-percha is then added to the 
compound. A sample compound is india rubber 10 parts, casein 
20, superoxide of lead 10, sulphur 3, and linseed oil 1. 

Ceramyl. — A material used in the finishing process in the 
manufacture of elastic web. Its use is to make the web stronger, 



160 GUMS AND BALSAMS 

and in a measure to act as a size, causing it to lie flat. It is 
also said to add strength to it. By the application of heat, cer- 
amyl, which comes in the form of a semi-solid, is reduced to a 
liquid. In English practice this is said to have driven out the 
use of glue in the dressing of elastic webs. Ceramyl is manu- 
factured in England. 

Cerasin, also spelled ceresin, is of a butter-yellow color, 
odorless, and has a specific gravity of .918 to .922. It is used 
chiefly in covering annunciator wires where the object is to pre- 
serve the colors of the yarns in the braiding. See Ozocerite. 

Cherry Gum. — A pale yellow or red-brown^ gum, coming 
from the bark of old cherry trees. It contains 35 per cent, of 
cerasin, 52 parts of arabicum, and 1 to 3 per cent, of ash. This 
gum is chiefly used in the manufacture and finishing of fine felt 
hats. The gums on the market are of two qualities, the Ger- 
man, which is the best, and the Italian. It is used in insulating 
instead of purified ozocerite, in certain cases where a little more 
adhesiveness is required. 

Coalite Pitch. — A residue of coalite tar, much like natural 
bitumen and containing little free carbon. An English product. 

Coal Tar. — See Tar. 

Colophane. — See Rosin. 

Colophony. — See Rosin. 

Coorongite. — The name given to a rubber-like mass found 
in Coorong, South Australia. Some place it among the fossil 
resins. Coorongite is not soluble in the ordinary solvents used 
in rubber work, but after mixing with india rubber, it can be 
put in solution. According to Forster, it vulcanizes somewhat 
as india rubber does. See Chapter II. 

Copal. — Hard copal is a fossil resin obtained from the East 
Indies, South America, and the Eastern and Western coasts of 
Africa. It occurs commercially in roundish, irregular pieces, 
having a specific gravity of 1.045 to 1.139. It is insoluble in 
alcohol, partially soluble in ether, and slightly so in oil of tur- 
pentine. Soft copal is obtained from living trees in New Zea- 
land, the Philippine Islands, Java, and Sumatra. Used with 
shellac, asphaltum, and arsenate of potash for waterproofing 



DAMMAR— ELATERITE 161 

leather; also in cements, in proofing compounds, and in var- 
nishes in connection with india rubber, lead, alum, and other 
ingredients dissolved in spirits of turpentine. 

Dammar is derived from the Amboyna pine, growing in 
the Malay peninsula, Sumatra, and Borneo. The resin exudes 
in tears and is collected after it has dried. It makes a very 
transparent varnish, the gum being soluble in benzine, essential 
oils, and to a certain extent in alcohol. Used in artificial leather 
compounds, and with rubber, asphalt, and fish oil for water- 
proofing leather. It is quite largely used in rubber cements. 
Specific gravity 1.10-1.12. 

Dextrine is an intermediate product between dextrose and 
starch. Specific gravity 1.04. It is soluble in cold water, and 
is much used as a substitute for gum arabic in mucilage, as it 
has strong adhesive properties. Cooley combined it with a little 
gutta-percha, resin oil, and earthy matters in the production of 
what he called artificial leather. It is used also in a mixture 
with plaster of Paris, making a tough surface mold for small 
experimental rubber work. 

Dextrose is obtained from starch generally, and is crystal- 
lized glucose. Specific gravity 1.39. It is soluble in water, and 
has many commercial uses. For example, it was used by Han- 
cock as a sizing for cloth on which was spread rubber in solu- 
tion, the dextrose being there in order to keep the rubber from 
sticking to the cloth. In other words, this was a sort of cheap 
calendering process. 

Earth Wax. — See Mineral Wax. 

Elastic Glue is used with india. rubber and gutta-percha 
in shoemakers' cements. See Substitutes. 

Elaterite is also known as elastic bitumen or mineral caout- 
chouc. It appears naturally in soft, flexible masses of a brownish- 
black color, somewhat resembling india rubber. It is composed 
of 85.5 per cent, of carbon, and 13.3 per cent, of hydrogen. In 
its physical characteristics, elaterite is found in infinite variety. 
It is sometimes elastic and so soft as to adhere to the fingers, 
and sometimes brittle and hard. One kind of it, when fresh cut, 
resembles fine cork, both in texture and color, and will rub out 
pencil marks. Its elasticity is due to its cellular texture, and to 



162 GUMS AND BALSAMS 

the moisture with which it combines. It is used to a certain 
extent in insulating compounds, but is intractable and so far 
shows no special features of value above other minerals of the 
same series. A few years ago a company was formed in Colo- 
rado which claimed to be able to make many kinds of rubber 
goods from this product alone, but little has been heard of the 
plan of late. See Gilsonite. 

Elemi comes from the Philippine Islands, and is a resin 
obtained from certain trees there. It varies from white to gray 
in color, and is quite soft and very tough. Alcohol and other 
solvents readily dissolve it, and its office usually is to give tough- 
ness to varnishes in which are harder resins. Used in connection 
with india rubber and benzine in the production of puncture 
fluids. Specific gravity 1.06. 

Euphorbium appears in the market in the shape of tears 
of irregular shape, varying in size from a small pea to 1% inches 
in length. Of a dirty gray or yellowish color, and very largely 
mixed with impurities. Must not be confused with Euphorbia 
rubber (which see). 

Fichtelit. — Occurs in a peat bed near Redmitz in the 
Fichtelgebirge in Germany, and also in fossil pines in the form 
of scales or flat needles. It has also been met with in Franzen- 
bad and in Denmark. A hydrocarbon little known, though 
mentioned in certain patented rubber compounds. 

Fish Glue. — Made by boiling the heads, fins, and tails of 
fish by high heat. Specific gravity 1.27. It is generally made 
into a liquid glue by a treatment with acetic or hydrochloric 
acid, whereby its property of gelatinizing is lost. It would have 
a disagreeable odor were it not for the fact that that is destroyed 
by adding cerosite or oil of sassafras or something of that kind. 
Fish glue is used in a cement for cured rubber, in connection 
with gutta-percha and rubber dissolved in bisulphide of carbon. 

Frankincense. — Also called olibanum (which see). 

French Asphalte. — See Auvergne Bitumen. 

Gamboge. — The best is found in commerce in cylindrical 
rolls of a dull orange-red color. Another form is that of lumps 
or cakes. Its powder is bright yellow and its taste very acrid, 



GILSONITE—GLUE 163 

but it has no smell. It is derived from a tree which is a native 
of Cochin China and Siam. Is used chiefly as a pigment. It is 
the basis of a general cement in which are also found rubber, 
alum, and burnt sugar, and in another is used with rubber, white 
lead, gum benzoin, alum, sugar, and sulphur, for cementing vul- 
canized rubber. 

Garnet Lac. — See Shellac. 

Gilsonite. — A hydrocarbon valued for its elasticity. Spe- 
cific gravity 1.10. One of the purest of crude bitumens, it is 
mined in the Uncompahgre Indian reservation, Utah, United 
States. It is a black, tarry-looking substance of brilliant luster. 
It is used for varnish making, in paints, and for insulation, 
either with or without rubber, one well-known compound con- 
sisting of rubber, linseed oil, and gilsonite. 

Glucose. — The commercial form is prepared from starch 
usually, as that is the cheapest raw material. The starch paste 
being boiled with mineral acids, dextrose, maltose, and dextrine 
are produced. Glucose in this country is made entirely of corn 
starch; in Europe, however, sago starch, rice, and potato starch 
are used. It is neutral, and both odorless and colorless. It is 
really a kind of sugar that is with difficulty crystallizable, and 
it is also called grape sugar. It occurs in commerce either as a 
thick, sweet, heavy liquid, or as a white, solid mass. It is used 
with rubber, glue, sugar, whiting, and glycerine in making book- 
binders' cements, and in making puncture fluids for pneumatic 
tires. Specific gravity 1.39. 

Glue. — An impure form of gelatin obtained from the horns, 
hoofs, skins, and bones of animals. Glue of good quality should 
be bright-brown or brown-yellow in color, free from specks, 
glossy, perfectly clear, hard, and brittle. 

Ground animal glue of ordinary quality has in recent years 
been employed as a colloidal filler in rubber compounding, par- 
ticularly in the manufacture of automobile tires and for other 
purposes where a tough wear-resisting quality is essential. Ow- 
ing to its nitrogenous composition glue acts as an accelerator 
in vulcanization. The annual consumption of glue in the Ameri- 
can rubber industry totals several million pounds. 

Glugloss Gelatine. — A gelatinous product used largely in 
America in waterproofing fabrics. It is dissolved in hot water 



164 GUMS AND BALSAMS 

to use, and makes an excellent waterproof sizing. A mixture 
of glycerine with it increases its elasticity. It combines readily 
with glue, dextrine, or any such products, and develops con- 
siderable adhesiveness. 

Gluten. — A vegetable substance obtained from wheat and 
other grains. Treated with tannic acid, it is used as a sub- 
stitute for gutta-percha under a formula by Johnson, who says 
the product can be vulcanized. Another formula calls for its 
mixture with oil and sulphur, as a substitute for gutta-percha. 
In cements it is the basis of one for uniting leather scraps, and 
is used with a little gutta-percha. 

Helenite. — Another name for fossil rubber or elaterite 
(which see). 

Idrialin (Idrialit). — A rare hydrocarbon found in Idria, 
a province of Austria, where it occurs with hepatic cinnabar. 
A similar body is obtained in the distillation of amber. Its 
specific gravity is 1.4 to 1.6. Mentioned in certain rubber 
formulas to assist the insulating qualities of compounds. 

Isinglass. — A glue substance prepared from the swimming 
bladders of certain fish. It is white and glistening, occurring 
in fibers or threads. The best is known as Russian, and comes 
from Astrachan. Its specific gravity is 1.2. On boiling isinglass 
it is converted into a very pure form of glue. Isinglass is used 
in quick-drying cements with india rubber, chloroform being the 
solvent. 

Jelutong Resins. — Jelutong or Pontianak contains two 
kinds of resin; one is soluble in acetone — easily in hot, less 
easily in cold. After acetone extraction Jelutong when sub- 
mitted further to the action of hot or cold sulphuric ether, or 
other solvents, yields the second resin, which is insoluble in 
acetone. Both resins are unsaponifiable and optically active. 
Their chemical composition is the same but molecular weights 
different, as are also their melting and boiling points. Probably 
they are secondary ethylene alcohols near to gum elemi, for 
which they may serve as substitutes. 

Patented solutions of jelutong resin are used as paint 
thinners and for priming coat on cement surfaces, not being 
attacked by the cement alkali. 



JUNIPER— LITHRO-CARBON 165 

Another and large use is as chief constituent in a compo- 
sition for coating wire box nails to cause them to hold firmly 
when driven into wood. 

Juniper is the gum known as sandarac, obtained from an 
evergreen growing in northern Africa. It occurs in small, light- 
colored grains, with a slightly bitter taste. It is soluble in tur- 
pentine oil and alcohol. Is used as an assistant in making perox- 
ide substitutes. Mixed with rubber and earthy matters and 
dissolved in turpentine, it was one of the early compounds for 
clothing. Its specific gravity is 1.05 to 1.09. 

Kauri. — An amber-like substance varying from a soft 
cream white to an amber color. It comes from New Zealand, 
and is also known as Australian dammar. The lighter colored 
kauri comes from living trees, but much of the darker is a 
fossil resin. It is cheaper than copal and largely used in 
varnishes. Kauri gum, in connection with rubber gum and 
pitch, is used for treating yarns used in insulated wire cover- 
ings. Parkes added it to rubber goods where the surface was 
to be printed upon after curing. One pound of sulphur formed 
Richards's covering for insulated wire. Its specific gravity is 
1.05. 

Lini. — A gum made from linseed, often used as a substi- 
tute for gum arabic. The seeds are first boiled in water for 
an hour, the resulting thick mass filtered, and then treated with 
twice its volume of 90 per cent, spirits of wine. A flocculent 
white precipitate separates, from which the dilute spirit can 
readily be decanted. The gum is clear, gray-brown, fragile, and 
dissolves in water. Two grams in 30 grams of oil is almost 
identical with an emulsion of gum arabic. In connection with 
coloring matters is the basis for the Knowlton patented water- 
proofing process. 

Lithro-carbon. — A kind of asphalt, large deposits of which 
are found in the state of Texas. It was at one time thought 
that it would supersede india rubber, and a company was formed 
with the idea of manufacturing goods from it. This was in 
1892, and india rubber is still used. The chemical composition 
of lithro-carbon is 88.23 carbon, 11.59 hydrogen, .06 oxygen, 
a trace of sulphur. Lithro-carbon is jet black in color, is flexible 



166 GUMS AND BALSAMS 

at ordinary temperatures, and is quite tough. Its specific grav- 
ity is about 1.028. It is said to be soluble in naphtha, benzol, 
bisulphide of carbon, etc. It will stand a temperature of 600 
degrees F., without giving off its associate products. It resists 
alkalies and acids, with the exception of concentrated nitric and 
sulphuric acids. Its manufacture was patented. Used with 
gutta-percha and shellac it makes an excellent insulator. 

Manila Gum. — See Gum Elemi. 

Manjak. — A kind of asphaltum of which there are exten- 
sive deposits in Trinidad, West Indies. Used chiefly in var- 
nishes. 

Mastic. — A resin from the shores of the Mediterranean. 
It occurs in tears of a pale yellow, is brittle, and of a faint 
balsamic odor. Specific gravity 1.07. It dissolves in acetone, 
turpentine oil, and alcohol, and is largely used in varnish. The 
residue obtained in the purifying of mineral asphalt is also called 
mastic. It is used in general rubber cements for joining stone- 
ware, earthenware, leather, etc. One of special value calls for 
10 parts of mastic to 1 part of india rubber, dissolved in chloro- 
form, and makes an excellent cement for fastening letters to 
glass. The gum also appears in many old-fashioned compounds. 

Menthol is obtained from the oil of peppermint coming 
from Japan and China, or from the oil of spearmint manufac- 
tured in the United States. Its melting point is about 108 de- 
grees to 110 degrees F., and it is slightly soluble in water, but 
freely in alcohol. It is often used in medicinal plasters which 
have rubber for a base. 

Mineral India Rubber Asphalt is the name of a material 
composed of refuse tar produced during the refining process of 
tar by sulphuric acid. It is black, like ordinary asphalt, and 
quite elastic. It is an excellent non-conductor of electricity, and 
is not assailed by acids or alkalies. In a naphtha solution, it 
yields a waterproof varnish for metallic objects, and is used in 
rubber compounding in place of asphalt. 

Mineral Tallow, also called hatchetine, is a substance 
found in Siberia, Germany, and Great Britain. It is an earth 



MINERAL WAX—OZOCERINE 167 

wax that is soft, flexible, and runs from yellow to yellowish 
white. It has no smell, and melts at from 115 degrees to 170 
degrees F. It is composed of 14 parts hydrogen and 86 carbon. 
Mineral tallow is used sometimes in place of earth waxes in 
insulated wire work, and has been used in paste blackings in 
connection with india rubber. 

Mineral Wax. — A term applied to several waxy-looking 
hydrocarbons found as mineral deposits, such as neft-gil, ozocer- 
ite, montan, and earth wax. It is found in Austria, and in the 
southern part of Russia, on the shores of the Caspian sea. In 
the United States it occurs largely in Texas and Utah. Used 
chiefly in insulating compounds. See Ozocerite. 

Myrrh exudes from the bark of a tree which grows in 
Arabia, in yellow drops that are quite oily at first, but which 
thicken and become hard and of a dark color. It appears in 
commerce in either grains, or tears, or in pieces of various sizes 
and irregular form, the color being red, reddish-brown, or 
yellow. Its taste is bitter and aromatic, and its smell balsamic. 
The best gum is known as Turkey myrrh. It is used with rub- 
ber, sulphur, and salicylic acid in complexion masks. Specific 
gravity 1.36. 

Natural Pitch is the name given to such kinds of pitch 
as are not manufactured, such as asphalt, bitumen, etc. — that 
is, pitch of a mineral origin, except that from coal or shale. 
See Asphalt. 

Oleo Resins. — A resin that contains a certain amount of 
the essential oil of the plant from which it exudes is so called. 
Chief among the oleo resins are certain which have a pungent 
taste and a peculiar, and often a pleasant odor, known as balsams. 

Olibanum. — The frankincense of the ancients, obtained 
chiefly from Asia and Africa. Specific gravity 0.863. It occurs 
in yellowish, somewhat translucent tears, with a balsam-like 
resinous smell, and an acrid aromatic taste. Sometimes called 
gum thus. It is largely used in the manufacture of porous 
plasters. 

Ozocerine is a vaseline-like substance prepared from ozo- 
cerite. There is also prepared from crude ozocerite a valuable 



168 GUMS AND BALSAMS 

black wax which, when mixed with india rubber, makes an 
excellent electric insulating material. This wax was recognized 
by a lecturer before the Society of Chemical Industry as the 
basis of the insulation known as okonite. 

Ozocerite. — A waxy hydrocarbon occurring in Austria, 
southern Russia, and the United States. It is also known as 
earth wax. Its specific gravity is 0.9 to 0.95, and it is about 
as hard as talc. Chemically, it consists of hydrogen 13.75 and 
carbon 86.25, while its melting point extends from 140 degrees 
to 170 degrees F. It is often found adulterated with asphalt 
and sometimes with Burgundy pitch. Purified ozocerite is 
known as cerasin. To make this, the crude material is treated 
with fuming sulphuric acid, and then filtered through charcoal. 
Thus prepared it is of a pale yellow color, the melting point 
ranging from 61 degrees to 78 degrees C. It has almost wholly 
driven out Stockholm tar as a protection for wires insulated 
with gutta-percha, when placed under ground. It improves the 
insulation, but in spite of common belief to the contrary, does 
not preserve textile fabrics. The best compound for the pro- 
tection of the insulation on wire consists of 3 parts ozocerite 
to 1 part of Stockholm tar. It is an insulator of high quality, 
and while it is in some ways intractable, its wax-like nature al- 
lows it to combine with other insulators or with textiles. It is 
also used as a water-repellent in fabrics, the gum being volatil- 
ized by heat, and the fumes passed through the cloth. As a 
surface covering for tapes or braids, it is often employed and 
is better than other gums, as it takes a fine polish from the 
polishing machine. The basis of Henley's system of curing india 
rubber core is melted ozocerite, which is used under pressure 
to remove all the moisture, being afterward heated in hot ozo- 
cerite, which stops up the pores. Ozocerite, mixed with india 
rubber, is also the basis of the india rubber compound called 
nigrite. It mixes, however, with difficulty with india rubber, 
which is an objection to many proposed uses of it. It also has 
a mildly deleterious effect on it. 

Paraffin. — A white waxy-looking body obtained from 
petroleum and certain tars by distillation. It is tasteless, in- 
odorous, harder than tallow, but softer than wax. Its specific 



PARAFFIN— PITCH 169 

gravity is .877. It is also obtained from ozocerite or earth wax. 
Its melting point varies with the source it is obtained from. It 
is insoluble in water and nearly so in boiling alcohol, but soluble 
in ether, oil of turpentine, oil of olives, benzol, and bisulphide 
of carbon. It is usually very free from water, and not liable to 
absorb it. It has been used as a waterproofing mixture and is a 
good insulator. When gossamer clothing was manufactured in 
large quantities, the surface of the goods before solarization was 
covered with a thin coat of paraffin, which gave it a peculiar shade 
until the solarization was completed, when all traces of the 
paraffin seemed to disappear. The insulating capacity of rubber 
to which paraffin has been added is quite remarkable, but at the 
same time it lessens the hardness of the rubber to a marked 
degree. Rubber dissolved in paraffin wax forms a curious com- 
pound which has been used in insulation. Paraffin is used in 
the artificial gums, like parkesine and insulite; also with cotton- 
seed oil and resin for cheap brattice cloth, and in cheap proofing 
compounds. It is not a great favorite as an insulator, as it 
shrinks in cooling, causing cracks. Paraffin tapes are also 
easily destroyed through the presence of free acid. It was 
formerly used largely in covering annunciator wires, but as it 
was found to absorb and retain water, its use was given up, 
and its place was taken by a compound of paraffin, cerasin, and 
resin. It is used in some rubber compositions for tubing- 
machine work to render the stock smooth running and give a 
fine finish. 

Pitch is the black residue that remains after the distill- 
ing of wood tar. Varieties are also obtained from coal tar and 
from bone tar. Wood pitch, however, has a toughness which 
the others do not possess. Specific gravity 1.07-1.10. Pitch 
was used very early in considerable quantities in hard-rubber 
compounds. Goodyear, for example, used considerable of it in 
hard compounds for coating metal, the rest of the compound 
consisting chiefly of rubber and sulphur. It is almost the only 
organic substance which largely increases the resiliency of india 
rubber. It is largely used in cements, and also in many rubber 
compounds. Equal parts of pitch and gutta-percha make a tire 
cement for fastening to the rims, known as " Davy's Universal 
Cement." It is used with gutta-percha in shoemakers' wax, and 



170 GUMS AND BALSAMS 

also in certain proofing compounds. Wood cements made of 
gutta-percha as a rule contain a certain amount of pitch. It is 
also used in the manufacture of Fenton's artificial rubber. 

Resins. — The term given to a number of complex bodies, 
generally the hardened exudation of sap from trees. Chemi- 
cally a resin is the substance obtained by the gradual oxidation 
of an essential oil. The specific gravity ranges between 1.02 
and 1.2. Resins are divided, as a rule, into three classes — hard, 
soft and gum resins. The former at ordinary temperatures are 
solid and quite brittle. They contain little or no essential oil, 
and are easily pulverized. Shellac and sandarac are good ex- 
amples of this kind, and soft resins are usually called balsams, 
and are either semi-fluid, or soft enough to be molded by hand. 
They are really mixtures of hard resins, and the essential oils 
found in the plant from which they come. On exposure to the 
air they become in time hard resins. Of this class are balsam 
of storax, tolu balsam, etc. Gum resins are the solidified milky 
juices of certain plants. They consist of a mixture of resins, 
essential oils, and a considerable proportion of gum. These are, 
for example, gum euphorbium, galbanum, and to this class also 
belong india rubber and gutta-percha. Most of the fossil gums, 
such as copal, are resins whose physical characteristics have 
been changed by their having been buried for a long time in the 
earth. These fossil resins are counterfeited to an extent by treat- 
ing ordinary resin with lime, which raises its melting point 
considerably. 

Retinite. — Also known as retin asphalt. It is a fossil 
resin found in brown coal. It is found in roundish masses of a 
yellow-brown or reddish color, is quite inflammable and readily 
dissolves in alcohol. At present it is somewhat rare, but if it 
ever should become common, it would undoubtedly find a place 
in rubber compounding. Its specific gravity is 1.07 to 1.35. 

Rosin is made from common turpentine, which is distilled 
in water, yielding nearly one-fourth its weight of essential oil, 
the residue in the retort consisting of common rosin. Rosin is 
also very generally called colophony, its true chemical name dis- 
tinguishing it from the other resins. There are two varieties 
of rosin in common use, the brown and the white. The first 



ROSIN— SHELLAC 171 

named is brittle, solid, and of an amber color, and comes from 
the Norway spruce fir. The white rosin is obtained from the 
pine and is known as galipot. Rosin dissolves very freely in 
alkaline solutions, which allows of its use in soaps. Its specific 
gravity is 1.08. There are three grades commonly on the market, 
which are called virgin, yellow dip, and hard. It is used in a 
great variety of rubber compounds, its chief uses being in fric- 
tions, dry heat varnishes, cements, and the puncture fluids. Al- 
most all lines of rubber manufacture use a certain amount of 
it at times. Only a small proportion of it can be used in rubber 
compounding, its office being usually that of the sticker. A large 
amount of it induces surface cracking, and often a decided 
blooming of the sulphur. It is also used in waterproof solutions 
in conjunction with spermaceti, india rubber, and paraffin wax. 
Mixed with boiling oil, it has been applied to gutta-percha arti- 
cles to give them a Japan-like luster, and is also important in 
gutta-percha glue, which is compounded of gutta-percha, pow- 
dered glass, litharge, and rosin. A very large use for it is in 
the rubber channel cements that are sold to leather shoe manu- 
facturers. 

Sandarac. — Also known as Gum Juniper (which see). 

Seedlac. — See Shellac. 

Senegal. — See Arabic. 

Shellac, Sticklac, Seedlac, Lac. — All these are different 
names for the same thing or different stages of its preparation. 
It is the exudation formed on several sorts of trees growing in 
the East Indies, but is chiefly produced from the banyan tree, 
the exudation coming from a scale-shaped insect known as the 
Coccus lacca, the female fixing herself to the bark and exuding 
the resinous substance from her body. In addition to the East 
Indian product there is what is known as Mexican lac, which 
exudes from the Croton draco. Sticklac is the resin as taken 
from the tree. Seedlac consists of fragments broken from the 
twigs and partly exhausted by water. Shellac is prepared by 
melting stick or seedlac, straining, and pouring upon a flat sur- 
face to harden. It is then washed, dried, melted, roughly refined, 



172 GUMS AND BALSAMS 

and sent to market, or it is poured into molds to harden and is 
known as button or garnet lac. The specific gravity of lac is 
about 1.139. It is partially soluble in alcohol, turpentine, chloro- 
form, and ether, and is completely soluble in caustic alkalies 
and borax solutions. Shellac was formerly used very generally 
in rubber manufacture in surface goods, and particularly in 
solarized goods in small proportions. It has a specific use to-day 
in the production of water varnishes for surface goods. It is 
also a constituent in the production of certain compounds in 
hard rubber, and particularly the semi-hard varieties, being used 
to the extent of 20 per cent, of the amount of gum. Although 
quite brittle, it seems to impart a certain elasticity to the product. 
The maximum use of shellac in a hard-rubber compound, ac- 
cording to Hoffer, is 88 parts india rubber, 50 parts shellac, 
and 12 parts sulphur. It is also used in certain of the Jenkins 
patented packings to the extent of 10 to 25 per cent, of the 
amount of rubber, where it is said to preserve the compound 
from the effects of coal oil, steam, or hot water. It is also 
used in many cements both with and without india rubber, one 
formula for marine glue being : 20 parts shellac, 12 parts benzol, 
and 1 part india rubber, mixed with heat. Dissolved in 10 
parts of strong aqua-ammonia, it forms a varnish for rubber 
goods, and is also used as a solution for re-varnishing old rubber 
shoes. Used with carburet of iron and bisulphide of mercury 
as a cement for card clothing, with india rubber and gutta- 
percha for attaching shoes to horses, in English " ale cement," 
and in certain proofing compounds. 

Size. — A weak solution of glue, sometimes used in shower- 
proof compounds and cements. The name size is also often 
applied to any thin viscous substance, as for instance, gilders' 
varnish. In rubber practice, however, the glue is what is or- 
dinarily employed. It is also used in preparing a perfectly 
smooth cloth upon which rubber is to be calendered, and from 
which it is stripped before the making up. See Glue and 
Gelatine. 

Sludge Oil Resin. — A heavy, gummy residue from the 
waste of superphosphate factories. Has been used with rubber 
in making Japan varnishes. 



STEARIN E— SPERMACETI 173 

Spruce Gum is used with chicle in the production of chew- 
ing gums. 

Stearine. — A white waxy-looking body obtained from fats 
— chiefly tallow and palm oil. When made from tallow it is 
called pressed tallow or tallow stearine, which is the solid part 
obtained from the heating of suet fat and the removal of the 
liquid part, which is oleomargarine. Tallow stearine is very 
largely used in candle making, where is found saponified stearine, 
distilled stearine, and distilled grease stearine. The usual spe- 
cific gravity of stearine is .920. This latter contains considerable 
cholestrol and differs from commercial stearic acid or stearine 
chiefly in its physical structure. Stearine is used in proofing 
compounds, in rubber blackings and in compounds containing 
resins. It has been suggested that a small proportion of stearine 
in certain rubber compounds that contain low grades of rubber, 
which in themselves have large proportions of resin, has a 
decided value in preventing oxidization. 

Stearine Pitch. — The brown, tarry residue left in the still 
during the process of refining tallow and fat. Used in the 
manufacture of certain packings that contain no rubber. Stearine 
pitch is also used as a lubricant for bearings that have a ten- 
dency to heat. 

Sticklac. — See Shellac. 

Stockholm Tar is used in black cements of the marine 
glue class, and is also used in rubber compounding, its office 
being to assist in the mixing of dry compounds, and as a bind- 
ing material for sulphur in the dry-heat cure. Also used in 
manganese cements and in cements to fasten tiles to floors. 

Spermaceti. — A peculiar fatty concrete substance obtained 
from the head of the sperm whale. Its specific gravity is 0.943, 
and it is fusible at 112 degrees F. Insoluble in water, soluble 
in hot alcohol, ether, and oil of turpentine, but redeposited as 
the liquids cool. Was formerly used in certain waterproofing 
compositions. 

Tar. — This substance is derived from the animal, vegetable, 
and mineral kingdoms. From the first, by the destructive dis- 



174 GUMS AND BALSAMS 

tillation of bones, is produced what is known as "Dippel's oil"; 
from the second, by the distillation of pine woods, the product 
is known as pine tar or Stockholm tar; and from the third, 
by the distillation of coal, is produced coal tar. Of the three, 
coal tar is the most used in rubber work, its office being to help 
carry adulterants in dry mixing and to keep the sulphur from 
blooming after vulcanization. It is used chiefly in dry-heat 
work. Goodyear discovered early that very large quantities of 
boiled tar could be used in connection with india rubber and 
sulphur without injuring the quality of the gum, and it has 
been very generally used since his time. 

Thus. — A name for gum turpentine, and rarely for oli- 
banum. Used with rubber and japan for waterproofing leather. 

Tolu Balsam is derived from a tree found on the moun- 
tains of Tolu, and the banks of the Magdalena river, in Colom- 
bia. It is very similar to balsam of Peru. It sometimes ap- 
pears in commerce in dry friable fragments, the newly imported 
gum being soft and tenacious. It is very fragrant and has a 
medicinal and tonic effect. Tolu balsam is used with paraffin 
wax and chicle in chewing gum compounds. 

Tragacanth is an exudation which comes in the form of 
translucent plates of a dull white, which water swells and partly 
dissolves. It is often used in mucilage in place of gum arabic. 
The gum comes from the Levant from the Astragalus gum- 
mifera. Has been used in connection with gutta-percha for 
making dental plates that are soft and adhesive to the mem- 
branes and that will not rot or deteriorate. 

Tragasol. — This is a gum produced from the kernels of 
the Ceratonia siliqua. The use of this gum as a solvent for 
india rubber, gutta-percha, or celluloid has been patented in 
England. A mixture of 25 parts of dissolved india rubber, 75 
parts of strong gum solution, with the addition of 1 part of 
carbolic acid to 500 parts of the mixture, makes a cement for 
wood, and a preservative paint against insects and vermin. 

Trinidad Asphalt is obtained from the pitch lakes of the 
island of Trinidad. Its specific gravity is 1.2, and it is some- 
what soluble in alcohol, while Persian naphtha, oil of turpen- 
tine, benzol, and benzoline readily dissolve it. See Asphalt. 



TURPENTINE— XYLONITE 175 

Turpentine. — This is a semi-solid resin, which comes from 
various species of pine as a rule. The chief commercial varieties 
are common turpentine, which comes from the Pinus palustris; 
Venice turpentine, from the larch; Bordeaux turpentine, from 
the Pinus maritima, and China turpentine, from the Pistacia 
lentiscus. Of these the Venice turpentine is said to be the best. 
It is of a pale yellow color, transparent, has a bitter taste, but 
a balsamic odor. Used instead of rosin in many compounds. 
Specific gravity about .90. 

Vegetable Pitch. — The residue left after distilling the tar 
made from wood of various trees. Called vegetable to dis- 
tinguish it from the mineral pitch, which is derived from coal. 
See Pitch. 

Xanthorrhcea Gum is somewhat similar to shellac, is 
abundantly produced in the Australian colonies, and sometimes 
used in the compounding of ebonite. Zanthorrhcea gum is also 
sometimes known as gum acroides, and is produced from the 
Australian grass tree. See Acroides Gum. 

Xyloidin. — An artificial gum much resembling pyroxylin 
obtained by the action of nitric acid on starch. 

Xylonite or Zylonite. — See Celluloid. 



CHAPTER X. 

PIGMENTS USED IN COLORING INDIA RUBBER. 

Most of the india rubber goods now manufactured are 
black, this color, if it may be so called, being produced in a 
measure by the color of the rubber, together with the leads and 
other ingredients, most of which darken during vulcanization. 
The next prominent color, from a rubber standpoint, is white, 
produced by either an oxide or sulphide of zinc. Next to this 
range the yellows and reds, produced by the sulphide of anti- 
mony, vermilion, and oxide of iron. 

So many colors are unstable when brought in contact with 
sulphur during the heat of vulcanization, and it is so difficult 
to get good effects, that it is hardly to be expected that beautiful 
colors in india rubber will ever become common. There are 
various methods used for changing the natural color of india 
rubber. The usual way is by incorporating, by mechanical mix- 
ture, earthy pigments or metallic oxides or sulphides, or vege- 
table coloring matters, which, by their covering property and 
strength, give to the india rubber their own particular shade. 
There are other methods, however. For example, there have 
been produced anilines soluble in benzine, that are used for sur- 
face work, such coloring being really an elastic enamel. Toys 
and minor articles that are ornamented in very bright colors, 
however, are generally painted over after vulcanization, but 
paint is not durable, nor does it long remain beautiful. 

While it is claimed ordinarily that it is impossible to dye 
india rubber, it should be remembered that the attractive colors 
that appear on children's toy balloons and similar pure-gum 
goods are applied as dyes, the colors being anilines, with methyl 
alcohol as a vehicle. These colors are boiled in rainwater, and 
when the solution is cold the balloons are put into the coloring 
liquid and turned so as to have their entire surface wetted. 
After that, they are dropped into cold water, which washes off 

176 



ANILINE COLORS 177 

the superfluous color. When this is done properly, the rubber 
does not give off any stain at all after the first washing. The 
colors used in this way are red, green, blue, orange, and pink, 
but other shades are equally available. 

Germany produced a full line of aniline colors soluble in 
benzine and for surface coloring of rubber goods they have been 
found very valuable. Although they are not absolutely fast, 
they are sufficiently so for all practical purposes. In many cases, 
these aniline colors, being soluble in benzine, can be mixed with 
india rubber — that is, when it is used in the form of solution. 
If the product be cured in open steam heat with sulphur, some 
very curious effects are likely to be obtained. This was proved 
at one time when a line of rubber colors was put on the market 
in the United States, with white oxide of antimony as a base, 
and anilines to give various shades. It does not often happen, 
however, that a problem of this kind confronts the users of 
aniline colors in rubber, the more general and sensible way being 
that of surface coloring. This is done in some cases by simply 
brushing the aniline color dissolved in benzine over the surface 
of the article. It is desirable, however, first to dip the goods 
in the dissolved mordant, and then to use the brush, if necessary. 
Where a high polish or a polished effect is desired, some sort 
of elastic lacquer must be put on over the coloring matter. A 
very thin india rubber solution is often used for this. 

In speaking of anilines, it must be remembered that those 
that have to be worked up with acids should be avoided for 
rubber work, but there are so many others that there is no need 
of the rubber man making this mistake. Where colors are to 
be printed upon rubber surfaces, a little dextrine is added to 
the aniline dissolved in benzine, and to make the color dry faster, 
a little sulphate of manganese mixed with half of one per cent, 
of alum and added to the mass is advisable. 

Black, blue, red, yellow and green anilines are" also used 
in coloring rubber cements that go to the leather shoe trade. 
These and other anilines are also used very generally in arti- 
ficial leather compounds. Aniline black is used in water var- 
nishes for luster coats and blankets. 



178 COLORING MATTER AND PROCESSES 

It is also a good idea to sponge the rubber surface with a 
water solution of alum before the color is applied. The use 
of alum as a mordant may be supplanted by bisulphate of soda, 
if it is desired. The best colors available in the aniline series 
are reds, particularly magenta reds, and the marine and alkali 
blues. 

A great many methods of surface coloring have been de- 
vised, some of them being ludicrous attempts at dyeing rubber. 
The surface of rubber is, of course, not easily affected by colors, 
unless it has first been attacked and roughened by some power- 
ful solvent. Malcolms' process for this surface coloring is per- 
haps as harmless as any. This method is to expose the rubber 
to the sunlight while it is immersed in alcohol. When the sur- 
face is somewhat disintegrated, the rubber is taken out, washed, 
and dipped in a dye solution. 

The colors that follow are described very briefly, and any 
rubber manufacturer can easily secure most of them for use 
or for experiment. 

BLACK. 

There are more methods of getting black rubbers than al- 
most any other color, as the tendency of the gum itself is to 
darken under heat and the action of sulphur, and the sulphides 
of most materials that are used in the compounding have the 
same effect. Most rubber goods are made up without regard 
to color, and are usually a dirty brownish-black, tempered by 
the yellow of the sulphur bloom. Where a genuine black is 
wanted, lampblack is one of the most common ingredients used. 

Black Hypo. — This is also known as hyposulphite of lead. 
It is really a mixture of thiosulphate of sodium mixed with 
acetate of lead, and appears as a fine white crystalline precipi- 
tate, which should be called thiosulphate of lead. There are 
two forms, the white hypo and the black hypo, the difference 
being that the white when heated is transformed into a soft 
black powder containing very little free sulphur. The black 
of the compound being sulphide of lead often contains over 
90 per cent, of pure sulphide. It is an excellent vulcanizing 



BONE BLACK— LAMPBLACK 179 

agent, and also a filler. When properly prepared it makes 
goods absolutely free from bloom. 

Bone Black (animal charcoatl), sometimes called ivory 
black, is a black powder obtained by grinding the product of 
bones that are burned at a red heat in close vessels. It is more 
dense and less combustible than lampblack. A good quality 
should have an even color, of a rather dull shade. The carbon 
content of bone black varies from 10 to 20 per cent., the rest 
being principally calcium phosphate combined with moisture and 
small amounts of impurities. Its specific gravity is 2.82-2.86. 

Carbon Black is the trade name given to lampblack made 
upon the surfaces of metal or stone by direct impact of flame, 
from which the black is removed by scrapers. Specific gravity 
1.73. The fuel employed is natural gas. Carbon black is much 
more intense in coloring effect than any other form of lamp- 
black and is preferred for rubber compounding. 

Other trade designations for carbon black are hydrocarbon 
black, gas black, satin-gloss black, jet black, silicate of carbon, 
Paris black, etc. 

Gas Black. — See Carbon Black. 

Graphite Blacks of late have been used very largely in 
rubber compounding and have done excellent work. They are 
not as black as the better grades of lampblack made from oils 
or resin. They are in many cases wholly inert, however, and 
therefore perfectly safe to use. One of the best types of this 
sort of coloring matter comes from a graphite mine in the 
United States. It is wholly amorphous, and has none of the 
flaky make-up that ordinary graphite has, but is 97 per cent, 
pure carbon. These blacks are said to give a brighter finish 
to varnished goods than ordinary lampblacks. The specific 
gravity of graphite varies from 2.17 to 2.32. 

Hydrocarbon Black. — See Carbon Black. 

Jet Black. — See Carbon Black. 

Lampblack. — Lampblack, however, is carbon in its amor- 
phous or spongy form. Specific gravity 1.68-1.70. It is ob- 



180 COLORING MATTER AND PROCESSES 

tained on a large scale by collecting the smoke produced during 
the combustion of oils, fats, resins, coal, gas, tar, wood tar, 
petroleum residues, dead oil, and even bituminous coal. This 
accounts for the various grades that are to be found on the 
market. Large quantities of lampblack are manufactured from 
natural gas and known as carbon or gas black. There are many- 
types of lampblack, the best in the world being employed in the 
preparation of india ink. This is made from burning camphor, 
a lower grade being made from the mixture of camphor and 
other oils. The smoke is collected on leaves, washed, dried, and 
sifted with the utmost care. 

The lines of rubber goods in which lampblacks are gen- 
erally found are rubber boots and shoes, black automobile treads, 
surface clothing, and carriage cloth, druggists' sundries (where 
the leads are deemed dangerous), and in certain compositions 
where emery is the chief ingredient used for grinding or polish- 
ing. A curious fact about lampblack is that a little bit of it in 
unvulcanized rubber seems to assist the erasive quality, and does 
not cause smutting. A little of it is also sometimes added to 
churning mixtures that do not readily mix. 

Lead Sulphide. — This is a valuable coloring matter for 
rubber, as it gives a good black, besides which it makes goods 
exceedingly resilient. There are great differences in the produc- 
tion of lead sulphides, but a good one is of special value to 
rubber manufacturers. Specific gravity 7.13-7.70. 

Paris Black. — See Carbon Black. 

Satin Gloss Black. — See Carbon Black. 

Silicate of Carbon. — See Carbon Black. 

Uranium Sulphide. — A fine black pigment more intense 
than plumbic blacks. It is a permanent color, and is said to 
be a preservative of rubber. 

BLUE. 

Blues are not largely used in general rubber work. They 
are found chiefly in toys, in sheetings, and in certain packings 



CHROME BLUE—SAXON BLUE 181 

Chrome Blue is manufactured from silica, fluor-spar, and 
chromate of potash. The resultant material is a deep blue 
vitreous mass which is reduced to an impalpable powder. It 
is less sensitive to acids than ultramarine, and is better adapted 
for rubber goods. 

Cobalt Blue is manufactured from oxide of cobalt, phos- 
phate of cobalt, and alumina. It is rarely used in coloring 
rubber where the ingredients are to be mixed with the mass, 
ultramarine being much superior. Also called smalts. 

Indigo Blue is prepared from plants of the Indigofera 
genus. Pure indigo is insoluble in water, nor is it soluble in 
weak acids or alkalies. A small percentage is dissolved in al- 
cohol and its solution is more considerable in turpentine. Indigo 
blue for rubber is said to be valuable on account of its pre- 
serving qualities, which are double those of other blues. Its 
specific gravity is 1.35. 

Molybdenum Blue. — A pigment recommended by Lascel- 
les-Scott is a bisulphide of molybdenum. It is an exceedingly 
beautiful blue, but costly. Large new deposits of this mineral 
have been found in the United States and Australia, and Nor- 
way, and it is likely to be so cheapened that it will be a valu- 
able rubber pigment. 

Prussian Blue (known also as Chinese blue). — A dark, 
brilliant blue compound, having iron for a base. There is a 
soluble and an insoluble variety of this compound which is of 
a somewhat complex chemical constitution. Heated strongly in 
the air, the insoluble form of Prussian blue burns like tinder. 
When boiled with caustic potash, it is decomposed. If the dry 
powder be strongly rubbed in a mortar, it assumes a copper- 
red luster. In commerce it occurs in irregular shaped masses, 
having a characteristic conchoidal fracture and copper-red luster. 

Saxon Blue is the original name of the pigment known 
to-day as smalts; it was also very frequently called enamel 
blue. Under this name was also sold a blue pigment made by 
mixing Prussian blue with alumina or a white clay. 



182 COLORING MATTER AND PROCESSES 

Smalts. — This is what may be called a deep tinted cobalt 
glass. The analysis of smalts of good quality is as follows: 

Deep- Pale- 

Colored Colored 
Norwegian German 

Silica 70.9 72.1 

Potassa (with traces of soda and lime) 20.4 20.0 

Oxide of cobalt 6.5 2.0 

Alumina .4 1.8 

Peroxide of iron .3 1.4 

Other earths and oxides, and loss 1.5 2.7 

Total 100.0 100.0 

This is one of the few colors that are practically inde- 
structible. In using smalts for the pigment, large quantities 
are necessary, as the color is not strong. 

Thenard's Blue is similar to cobalt blue, but is a more 
beautiful pigment. It is used chiefly as a surface color. White 
pigments in small quantities added to this blue make beautiful 
turquoise colors. 

Ultramarine. — This is the most important blue used in 
rubber. Its composition is essentially the same whether genuine 
lapis lazuli or artificial. Artificial ultramarine is equal and often 
superior to the natural pigment. This is made of kaolin, car- 
bonate of sodium, willow charcoal, and sulphur. The follow- 
ing analysis of the natural ultramarine is given: 

Silica 37.6 

Alumina 27.4 

Sulphur 14.2 

Soda 20.0 

Analyses of the best artificial ultramarines show these 

figures : 

Silica 40.25 39.39 40.19 

Alumina 26.62 24.40 25.85 

Sulphur 13.42 12.69 13.27 

Soda 19.89 21.52 20.69 

Ultramarine appears in commerce as a fine blue powder 
of various standards of fineness. Acids readily destroy it, but 
alkalies have no effect on it. It stands heat well, not changing 
below a low red. It is used in cements for backs of memo- 
randum blocks, and in blue soft rubber goods, particularly in 
vapor-cured goods, such as sheeting. When mixed with chrome 
yellow it makes a green ; with colcothar, it makes a violet. 



YALE BLUE—TERRA-VERTE 183 

Mixed with rose pink, oxide of zinc, and Indian red, it pro- 
duced the well-known wine-colored coat that was so popular 
a few years ago. It is claimed that ultramarine blue keeps 
rubber from overcuring, and that it is, therefore, a most useful 
ingredient to add to compounds that are exposed to heat. A 
very little ultramarine blue added to a black in rubber some- 
times overcomes the grayish shade. A small amount of blue 
added to white dispels any yellowish tint and consequently im- 
proves the whiteness of the goods. 

Yale Blue. — In certain soft rubber goods, where a strong 
blue is needed, ordinary ultramarine was found unsatisfactory. 
A firm of rubber chemists therefore produced Yale blue, which 
is a strong coloring matter, and wholly inert as far as the rub- 
ber is concerned. Yale blue is an ultramarine entirely free of 
alum and gypsum. 

GREEN. 

It is fortunate that greens are not largely sought in the 
rubber industry, for they are rare. Arsenic greens in many 
cases are not to be thought of ; therefore, about the only ones 
that are available, unless very high cost goods can be utilized, 
are the following: 

Chrome Green. — A coloring matter that is not affected 
by strong acids, or alkalies, and which is inert when mixed 
with india rubber. Specific gravity 4.91. It is the best mineral 
green that can be used in connection with rubber. It is really 
a sesquioxide of chromium; and may be mixed with rubber, 
with any kind of solvent, and with other oxides and pigments, 
without hurt to the compounds. 

Hungarian Green is a similar pigment found at Kern- 
hausen in Hungary. These greens in some respects resemble 
the article now known as terra-verte. 

Saxon Green is a green earth of a clayey nature, found in 
parts of Saxony. Its specific gravity is 5.04. 

Terra-verte is of mineral origin, and is imported in large 
quantities from Italy. It is a pale neutral green of moderate 
cost, and is not injurious to rubber. On analysis it shows, as 



184 COLORING MATTER AND PROCESSES 

in the following table, the chemists quoted beeing Klaproth for 

No. 1 and Berthier for No. 2: 

No. 1 No. 2 

Silica 51.50 46.00 

Alumina 12.00 11.70 

Protoxide of iron 17.00 17.40 

Lime 2.50 3.00 

Magnesia 3.50 8.00 

Soda 4.50 

Water 9.00 13.90 

Ultramarine Green is made by a process very similar 
to that made in producing blue of that name, and its action 
upon rubber is almost identical with that of ultramarine blues. 

red and brown. 

The strong red coloring matters used in hard rubber work 
are mostly of a mercurial base. These are vermilion, red chro- 
mate of mercury, sulphide of mercury, and iodide of mercury. 
The Chinese vermilion, which is the best, is prepared by a 
special process of their own, and contains 89 per cent, of pure 
mercury, the rest being sulphur. This coloring matter is used 
very largely in dental vulcanite, small amounts of it also giving 
excellent shades in soft rubber goods. Cinnabar and Paris red 
are also mercurial sulphides, and very strong colors. The sul- 
phides of mercury are really the only ones that are safe and 
valuable for producing these colors. Red chalk and natural 
clay containing a certain amount of iron are used chiefly as 
fillers in rubber goods, although a certain quantity of them pro- 
duces a dark red color. 

Antimony Crimson Sulphide. — This is altogether the 
best antimony color now in use. It gives a fine shade of 
orange or red. Specific gravity 4.20. 

Colcothar. — A form of oxide of iron of specific gravity 
4.8 to 5.3. It is the acid free calcined residue of iron pyrites 
from the manufacture of sulphuric acid. The least calcined 
portions, scarlet in color, are termed jewelers' rouge, and the~ 
more calcined parts, of bluish shade, are called crocus. Its 
composition is ferric oxide. In its reaction it is indifferent, 
being very stable under ordinary conditions. Colcothar is a 
dull red and is often used in red packings, solings, etc. 



HEMATITE— VENETIAN RED 185 

Hematite. — An ore of iron, somewhat soft and friable. 
Specific gravity 5.19 to 5.28. Composition 70 per cent, iron, 
30 per cent, oxygen. Insoluble in water, alcohol, or rubber 
solvents. As a colorant in rubber work it is unchangeable 
chemically. Used in packings and for red maroons. 

Indian Red. — A deep rich iron oxide red, made in dif- 
ferent shades and purities. 

Iron Oxide. — Pure bright iron oxide, made by calcining 
iron sulphate. It contains 96 to 98 per cent, of iron sesquioxide, 
the remainder being silica. The cheaper grades sometimes con- 
tain water of crystallization. The better grades are prepared 
by wet grinding in buhr and pebble mills. See Colcothar. 

Iron Peroxide. — An old name for the sesquioxide of iron. 

Orange Vermilion, crystalline lead chromate, gives a 
very handsome color in connection with rubber, but is rarely 
used, as it is not permanent if other metals, such as copper, 
brass, iron, and zinc, come in contact with it. Specific gravity 
6.12. 

Oximony. — A special brand of red oxide of iron for the 
rubber trade. It has about four times the color strength of 
sulphuret of antimony. 

Prince's Metallic Paint. — An impure oxide of iron of 
variable analysis containing much silica and alumina. 

Prussian Red is an oxide of iron prepared from cop- 
peras, and, therefore, it is the same as the modern rouge or 
oxide of iron. 

Red Ocher. — An impure oxide of iron. A dull-red earthy 
substance containing clayey matter, and having a specific gravity 
of about 5.2. Used chiefly as a filler, as the color is not strong. 
As far back as the time of Dr. Mattson, red ocher, Venetian 
red, and Indian red, were advised by him for use in rubber 
compounding. Indeed, he obtained a patent for packing in 
which Venetian red was the principal adulterant. 

Venetian Red. — The usual composition of Venetian red 
is a combination of ferric oxide and calcium sulphate in the 
proportion of 20 to 40 per cent, of the former to 60 to 80 of 



186 COLORING MATTER AND PROCESSES 

the latter. It is made in the dry way by heating ferrous sul- 
phate with lime. It is inferior in pigment effect to ordinary 
iron oxide. The color is dull brick-red. 

Vermilion. — The red form of mercuric sulphide is a scar- 
let red powder of specific gravity 8.12. It is sometimes adul- 
terated with red lead or red oxide of iron, but such adultera- 
tions can be detected by heating a small sample of the sus- 
pected article on a porcelain or platinum dish. If any adulter- 
ant is present it will remain behind as a residue, since pure 
vermilion is completely volatile. This substance is sometimes 
called cinnabar. A substitute for vermilion in hard rubber was 
brought out by John Haliday in 1870. This was a mixture 
of garancine and cochineal, in water solutions, boiled and mixed 
in the proportion of 5 parts of garancine liquor to 1 part of 
cochineal liquor. To each gallon of this compound liquor 2 
pounds of pure oxide of antimony were added; then heating 
until the water was evaporated and the new coloring matter 
perfectly dry. Another vermilion substitute was antimony 
crimson sulphide. According to A. D. Schlesinger, veteran 
hard rubber expert, antimony crimson sulphide, when mixed 
with india rubber and sulphur, will, during vulcanization, im- 
part to hard rubber a light red color very similar to that 
obtained by the use of vermilion. The proportion of sulphur 
is the same as is used ordinarily in making vulcanite, while 
to each pound of rubber are added 12 ounces of crimson sul- 
phide of antimony. 

WHITE. 

Only a few colors are available for use in making white 
rubber goods. Of these, the zincs take the lead, being by far 
the most constant and valuable. They lend their color to the 
mass simply by their presence as dry paints with strong color- 
ing qualities. 

Barium White. — This is also called constant white, or 
blanc fixe, and comes from the sulphate of barium or heavy 
spar. In treatment, it is ground very fine, treated with hot 
hydrochloric acid, washed, dried, sifted, and then forms a fairly 
white, dense, impalpable powder. Artificial barium sulphate or 



BECKTON WHITE— CALAMINE WHITE 187 

blanc fixe is obtained by precipitation from a solution of barium 
chloride with a solution of sulphate of soda. It is identical 
with the mineral barytes in all of its chemical properties. It 
is a brilliant white of exceedingly fine grain. It is highly es- 
teemed in rubber compounding and has a specific gravity of 
4.20. This is somewhat less than the specific gravity of natural 
barytes. It is one of the few metallic colors that the German 
anti-poison act allows manufacturers to use in any way they 
please. See Barytes. 

Beckton White. — See Lithopone. 

Borate of Zinc. — A zinc salt, precipitated by 20 to 30 per 
cent, of a soluble borate, the result being a white powder, which 
is claimed to have a distinctively preservative influence when 
used in rubber, while the tensile strength of the gum is much 
enhanced. 

Bougival White was a fairly common white pigment, 
although it has been replaced by barytes, terra alba, and whit- 
ing. Bougival white is a white, marly, China clay found at 
Bougival, near Marly, in France. The district surrounding 
Bougival and also Normandy and Auvergne contains many beds 
of white clays, notable for their smooth qualities of good color. 
Roughly Bougival white contains 33 per cent, chalk (carbonate 
of lime) and 67 per cent, kaolin (hydrated silicate of aluminum). 

Calamine White. — This is prepared from the native car- 
bonate of zinc, by calcining and grinding. It is not a strong 
white, and is not nearly as good as the oxide or carbonate of 
zinc as a coloring matter. For a cheap white, and a filler, 
however, it is useful. Although the German anti-poison act of 
1887 prohibits the use of zinc as a coloring matter, it does 
not apply to its ordinary use in rubber compounding. They 
rule that zinc compounds not soluble in water may be used in 
rubber when and where the coloring matter is mixed in the 
mass before vulcanizing, or as a pigment on the surface if it is 
covered with a lacquer varnish. Specific gravity from 4.30 to 
4.50. 

Charlton White. — See Lithopone. 



188 COLORING MATTER AND PROCESSES 

Chinese White. — Another name for Zinc Oxide. 

Faro's Spanish White. — Also known as pearl white. A 
trinitrate of bismuth, and a white that, it is said, has a future 
in rubber compounding. It is not easily affected by atmos- 
pheric influences, or by the action of sulphurous compounds. 

Fulton White. — See Lithopone. 

Griffith's White is a sulphide of zinc of English manu- 
facture, prepared by precipitation, and containing a certain pro- 
portion of magnesia. 

Kremnitz White was the name of a somewhat indefinite 
white. In some cases it was applied to white lead, but in others 
was given to bismuth white (oxide of bismuth) and often to 
white oxide of tin. 

Lithopone (also Lithophone). — A white pigment made 
by precipitating sulphate of zinc with barium sulphide. The 
barium sulphide is made from the native barytes by heating 
with charcoal,, which reduces the sulphate to sulphide and poly- 
sulphide, which are soluble in water. The zinc sulphate is made 
by roasting zinc blende or the ore "black jack" under oxidizing 
conditions, which forms soluble sulphate of zinc. Both sub- 
stances are dissolved in water, which frees them from many 
impurities, and the two solutions mixed, when zinc sulphide and 
barium sulphate both precipitate out as fine powder mixed with 
free sulphur from the polysulphide. The powder is dried and 
roasted, which drives off free sulphur and produces some free 
zinc oxide. Gives a fine white, but may turn gray on long ex- 
posure to light. This defect is not so bad for rubber as for 
painting. It is a constant white, and is largely used instead of 
oxide of zinc for white goods, particularly in the manufacture of 
druggists' and surgical sundries. The commercial article contains 
70 per cent, of barium sulphate and 30 per cent, sulphide of 
zinc. Its specific gravity is 3.6 to 4.1. 

Moudan White or Morat White. — This white came 
from the Pays de Vaud in Switzerland, Moudan and Morat 
being two towns in that district. It was a fine white clay with 
a silky luster and a fine grain. It resembles Spanish white and 
was often used in place of it. 



OLEUM WHITE— ZINC OXIDE 189 

Oleum White. — A high grade of sulphide of zinc, in 
which is a certain proportion of blanc fixe. It is a trifle heavier 
than a pure sulphide of zinc, but in practice has been found 
to be equal to if not better than either the sulphide or oxide 
of zinc in the manufacture of certain white rubbers. It is 
essentially lithopone. 

Orr's White. — See Lithopone. 

Ponolith. — Another name for Lithopone. 

Ross's White. — See Lithopone. 

Rouen White was a marly clay found near Rouen in 
France, prepared for use by levigation. In most respects it 
resembles Bougival white. 

Rubber Makers' White. — Another name for Lithopone. 

Spanish White is a name now often given to a good 
quality of whiting, but originally given to a good kaolin clay 
prepared for sale first by levigation, then by treatment with 
vinegar, which separated out any calcium carbonate it contained, 
then washing well and drying. 

Troye's White is a carbonate of lime, and, therefore, was 
in all respects like the modern whiting. It was a very common 
pigment at one time and much used for a variety of purposes. 
Specific gravity about 2.70. 

Zinc Carbonate. — This is a form of zinc rarely known 
today in rubber mills» The first white rubber, however, was 
made of it under a patent granted to the late Henry G. Tyer. 
It is a white powder, of the specific gravity of 4.45, and is made 
by mixing a solution of equal quantities of sulphate of zinc and 
carbonate of sodium, and subsequently the boiling of the white 
precipitate formed for a short time. 

Zinc Oxide is used more than any other coloring matter 
in the production of white rubber. It is especially valuable be- 
cause during the process of vulcanization it increases the white- 
ness of the goods. This is because the part of the zinc oxide 
that is turned into the zinc sulphide is a stronger white than 
the first. Oxide of zinc made of pure spelter is the best. Where 
lead and zinc ores are found together it sometimes happens that 



190 COLORING MATTER AND PROCESSES 

the oxide contains a certain amount of lead, as lead sulphate, 
and then its value as a coloring matter is injured. 

Zinc oxide is prepared by two processes : French process, 
in which spelter or metallic zinc is the raw material, and 
American process, in which ores of zinc are the raw materials. 
French process oxides of American manufacture are known as 
" Florence zinc." 

French process zinc oxide is sold in three grades, designated 
as "White Seal," "Green Seal" and "Red Seal." 

White Seal is brilliantly white, of large volume and ex- 
treme fineness. It weighs 150 pounds to the barrel, as com- 
pared with 300 pounds of other oxides. 

Green Seal is equal in brilliancy of color to White Seal, 
but is less voluminous. 

Red Seal is the cheapest of the three grades and is neither 
so white nor so smooth in texture as the others. 

American process zinc oxides for the rubber trade are of 
two brands, " Special " and " XX Red." 

Special is particularly free from lead, containing less than 
0.1 per cent, of protoxide. It is intended for use in compound- 
ing white rubber and can be used in any mixture without chang- 
ing color. It is very smooth and free from mechanical im- 
purities. 

XX Red is an oxide for mechanical rubber goods, free 
from mechanical impurities. It contains up to 0.2 per cent, 
of protoxide of lead and is not so white as the "Special" brand. 
The specific gravity of zinc oxide is 5.61. It is sometimes 
known as Chinese white. A certain percentage of this oxide 
is often added to dark-colored goods to increase the resiliency 
of the rubber. It also increases the hardness of a compound 
where soft gums are used. Manufacturers in insulated wire 
find that it increases the insulating qualities of rubber when 
added in moderate quantity. 

A very simple test for zinc oxide is as follows : Put a small 
quantity in a test tube or vial and add diluted muriatic acid 
(such as can be obtained in any drug store) ; agitate to dissolve 
all lumps, and if it be commercially pure oxide of zinc, no residue 



ZINC SULPHIDE— GOLDEN SULPHIDE 191 

will remain. The only adulterant likely to be found which would 
not leave a sediment would effervesce violently. Should the 
addition of acid to the pigment produce sulphureted hydrogen, 
the odor of which is unmistakable, no doubt would exist that the 
sample is not oxide of zinc and probably a much cheaper pig- 
ment. There are many pigments on the market called zinc and 
containing some zinc in various forms, which have their uses, 
but should not be confused with straight oxide of zinc. 

Zinc Sulphide. — This is a white that is fully equal to the 
popular oxide, and does not alter its tint under the influence of 
sulphur and heat. It is said to exert a distinctly preservative 
action upon india rubber. Sulphide of zinc, pure and in com- 
bination with other materials, and under various names, has been 
sold very largely to rubber manufacturers. It is deemed espe- 
cially valuable in white goods cured with dry heat. It is used 
in high grade white stocks, and in pink dental rubber. It also 
assists in the vulcanization of rubber. Zinc oxide may be re- 
placed entirely or in part with zinc sulphide pigment. The 
manufacture of zinc sulphide whites is an intricate chemical 
process. They are chemically made by a double precipitation 
process, are furnaced at a very high temperature, and carefully 
washed and dried, producing a white of exceptional strength 
and body. No white pigment made possesses greater uniformity 
than the standard makes of zinc sulphide whites. The specific 
gravity of zinc sulphide is 3.98. 

Zinc White. — This is another name for Zinc Oxide. 

YELLOW. 

Yellows are not often demanded in rubber work, except 
in a few fancy articles and labels. The most common is that 
produced by the golden sulphuret of antimony, but color is not 
what is sought in the use of that ingredient, but rather the ex- 
cellent rubber produced by it when used instead of sulphur. 
Other mineral yellows used are strontium, chromium, cadmium, 
barium, and zinc compounds. 

Antimony Golden Sulphide. — This is the pentasulphide 
much used for high-grade red rubber goods, although its color- 
ing effect is mild and it is esteemed rather for its influence on 



192 COLORING MATTER AND PROCESSES 

the texture and quality of vulcanized rubber. See under vul- 
canizing ingredients. 

Arsenic Yellow (also known as King's yellow), is a term 
applied to sulphide of arsenic. A cheap grade of this, which 
is really only an imitation, is manufactured by mixing together 
litharge and white arsenic, and grinding the product. Either 
of these, of course, is poisonous, and they are very rarely used 
or needed in connection with rubber. The specific gravity of 
arsenic yellow is 3.48. Although a sulphide, there is not enough 
sulphur in its composition to vulcanize india rubber. On account 
of its poisonous properties, this yellow has been largely super- 
seded commercially by the comparatively harmless chrome yel- 
lows. Another name for this color is orpiment. It was often 
used in rubber compounds of twenty years ago. A small quan- 
tity in white zinc stock takes off the glaring white effect, and 
produces a handsome cream white. It must be an impalpable 
powder to bring out the color. 

Aureolin. — A very handsome color, and one that is stable 
and brilliant. It is a double nitrite of cobalt and potassium. 
The color stands the light well, and sulphur compounds have 
little influence upon it. This is chiefly used for surface work. 

Barberry Yellow. — Made from the root or bark of the 
Barberis vulgaris. It is largely used in coloring leather surfaces, 
and, in connection with gamboge, is said to be useful in rubber 
work. 

Cadmium Yellow. — This is cadmium sulphide and is the 
best pigment for producing yellow in a rubber compound. It 
does not injure the elasticity or strength of the india rubber in 
any way, and, while it has no special effect on vulcanization, 
perhaps hurries it a little. It is not injurious to the health of 
persons using it, and is generally used for surface ornamen- 
tation of toys, etc. It is sometimes mixed with yellow sulphide 
of tin to cheapen it. While cadmium was ruled against in the 
German anti-poison act, the sulphides of this metal were made 
an exception and said to be safe. In dental plates, however, 
where the coloring matter was used in large quantities, it was 
advised against. The costliness of cadmium yellow bars its 
general use in rubber. Its specific gravity is 4.58. 



CHROME YELLOW— ZINC YELLOW 193 

Chrome Yellow. — Ordinarily the chromate of lead, which 
is largely used as a pigment. It is somewhat poisonous and is 
apt to oxidize organic substances, particularly if sulphur be 
present. Has been used in the surface ornamentation of rubber 
toys, but such use is generally condemned. The only chrome 
yellows that are really valuable for rubber work are the chromate 
of zinc, or possibly the chromate of strontium. 

Cobalt Yellow. — This is another name for aureolin. 

Dutch Pink is the name given to some common yellow 
lake pigments made from Persian berries, quercitron bark, fustic, 
etc., on a base of China clay or whiting. At one time a blue 
Dutch pink was known, prepared from the woad plant. 

Gamboge Yellow. — Obtained from the Garicinia morella. 
It contains from 20 to 25 per cent, of gum, 65 per cent, of resin, 
3 per cent, of volatile oil. It is soluble particularly in spirits, in 
a number of oily liquids, and partially in water. Finely pulver- 
ized gamboge may be mixed with rubber, and is said to be a 
preservative of it. 

Yellow Ocher. — There are several ochers, all of them 
being practically oxides of iron mixed with clay. They are earthy 
substances of no particular reaction, very stable, having a specific 
gravity of about 5.00. Their low cost renders them available 
for almost any work, but the colors produced are not especially 
beautiful. 

Zinc Yellow. — This color is chromate of zinc and potas- 
sium. It is of light lemon color and permanent. It is not af- 
fected by sulphur and can be mixed with other pigments. 



CHAPTER XI. 

ACIDS, ALKALIES, AND THEIR DERIVATIVES USED 
IN RUBBER MANUFACTURE. 

As a rule neither acids nor alkalies, in the strict sense of 
the term, are largely used in ordinary rubber compounding. In 
a great many of the processes, however, that go far to make up 
finished goods, acids are used, as, for example, in those employed 
in the reclaiming of rubber chemically. Alkalies also are most 
necessary, a notable example being the use of caustic potash and 
caustic soda solutions in removing sulphur from manufactured 
goods. A great variety of uses other than these may be indicated. 

Acetic Acid. — This is usually obtained by the dry distilla- 
tion of wood, peat, or sawdust. The strongest form is known 
as glacial and occurs in large watery crystals, readily liquefied. 
The common commercial acid usually has a brown or yellowish 
color, due to impupty. The pure acid is colorless. Its specific 
gravity is 1.05, and it has the characteristic odor familiar in 
vinegar. As an acid it is not very corrosive, and its compounds 
are easily decomposed by mineral acids. It is quite volatile. 
The primary use of this acid in connection with india rubber is 
in the coagulation of rubber milk. It is a prominent component 
part of the smoke used in coagulating fine Para rubber. It has 
also been used in the Vaughn process for coagulating balata, and 
in the manufacture of certain substitutes like linoxin, parke- 
sine, etc.; in connection with nitro-cellulose and castor oil in 
the production of certain waterproofing compositions; by Broo- 
man in separating whiting, white lead oxides, etc., from vulcan- 
ized rubber; and in shoemakers' blackings in connection with 
caoutchouc oil, vinegar, molasses, and lampblack. 

Alum. — A general term for several chemical compounds of 
aluminum, potassium, chromium, and ammonium. Common alum 
is the double sulphate of potassium and aluminum, having a 

194 



ALUM— ALUMINUM SULPHATE 195 

specific gravity of 1.7 and containing 45 per cent, of water of 
crystallization, one-quarter of which is expelled on heating to 
140 degrees F. It is soluble in water 9% parts per 100 when 
cold, 357 parts per 100 when hot. Chrome alum is a double 
sulphate of chromium and potassium, its specific gravity being 
2.7, and containing 43 per cent, water of crystallization, which 
is almost entirely lost at 392 degrees F. It occurs as dull purple 
crystals, slowly soluble in water to 20 per cent, in the cold and 
50 per cent, in hot water. Its action on gelatine is remarkable 
for its hardening qualities. Ammonia alum, the double sulphate 
of aluminum and ammonia, is largely used in place of common 
alum. It contains 48 per cent, of water of crystallization and 
has a specific gravity of 1.63. Strongly heated, it yields sulphate 
of ammonia, water and a very small quantity of sulphuric acid, 
while alumina is left behind. It is soluble in water 13 per cent, 
cold, 422 per cent. hot. Roman alum has the same general 
characteristics as common alum, but contains a little more 
alumina. 

Alum is used in many of the shower-proof mixtures for 
cloths of the cravenette order, that are today bought and made 
up by manufacturers of mackintoshes. It is also sometimes 
used in the manufacture of sponge rubber. By Garnier's 
process it is also used in spirituous solution to cure rubber with- 
out heat by mixing with it. Used also in Wray's substitute 
for gutta-percha. Alum was used in Payne's gutta-percha com- 
pounds for proofing, varnishing, and paints. Ghislin, who pre- 
pared some curious compounds from seaweed and india rubber, 
mixed alum, gelatine, and metallic oxides in his compounds. It 
is also sometimes used with sulphate of iron and soap, in a 
water mixture with boiled linseed oil, to make flexible water- 
proofing compounds. 

Aluminum Sulphate. — The active principle of alum. 
Often sold as concentrated alum. Occurs commercially as white 
square cakes, somewhat transparent, and capable of being cut 
with a knife. Readily soluble in water, and contains a small 
quantity of free sulphuric acid, potassa, and soda alum. Its 
specific gravity is about 4.00, water of crystallization 48 per 
cent. Its composition indicates a usefulness in compounding 



196 ACIDS AND ALKALIES 

sponge rubbers. Used in linseed oil compounds, for wagon 
covers. See Alum. 

Ammonia, at ordinary temperature, is a colorless gas of 
well-known odor and sharp, biting taste. It is usually met with 
in the arts in watery solution, the specific gravity of which 
varies with the amount of ammonia gas dissolved. The strongest, 
sometimes called caustic ammonia, contains 32.5 per cent, of the 
gas, and has a specific gravity of .875. Ordinary commercial 
ammonia contains 9.5 per cent, ammonia gas and its specific 
gravity is 0.96. The weakest usually has a percentage of 5.5 
and a specific gravity of .978. Ammonia has a powerful solvent 
action upon sulphur, is alkaline in its nature, and very volatile, 
so that much care is requisite in handling it. It has long been 
known to have a preservative effect upon india rubber; for ex- 
ample, low grade African rubbers are often treated with am- 
monia to neutralize the smell, and also to toughen the rubber. 
In the cold-curing process a saucer of ammonia put in the bot- 
tom of the vapor room will effectually neutralize the fumes of 
chloride of sulphur. It is also advised to wash with an ammonia 
solution vulcanite that has begun to perish. Soft rubber goods 
also are preserved, according to Dr. Pol, by the immersion for 
an hour in a solution made of 1 part of ammonia, and 2 parts 
of water. 

Sievier dissolved india rubber in ammonia, leaving it in a 
closed vessel for a long time, after which he heated the solution 
and absorbed the ammonia gas in cold water. Concentrated 
liquor of ammonia is added to milk of the rubber tree to pre- 
serve it for transportation. Where vegetable fibers are reduced 
to cellulose and mixed with india rubber, the rubber is first 
steeped in ammonia and then dissolved in some suitable solvent. 
Newton mixed ammonia with india rubber and gutta-percha, and 
then treated the gum with chlorine, making a white, hard com- 
pound, which he claimed would stand all varieties of climates, 
acids, greases, etc. 

Ammonium Carbonate, obtained during the dry distilla- 
tion of coal in the manufacture of illuminating gas, is a white 
crystalline powder of very penetrating smell, from which quality 
it takes its popular name of smelling salts. Exposed to air, it 



AMMONIUM CHLORIDE— ANILINE 197 

decomposes, evolving ammonia and becoming converted into 
bicarbonate. It is used industrially for the removal, of grease 
from cloth and cleaning woolen fabrics. Carbonate of ammonia 
is used also in the manufacture of sponge rubber, and in hollow 
work, where its expansive force is utilized to mold the article 
effectually. 

Ammonium Chloride. — Also known as muriate of am- 
monia, or sal ammoniac. Obtained largely from gas works liquor. 
Specific gravity 1.5. Usually occurs in small crystals. When 
dissolving in water a considerable reduction of temperature 
occurs, and this has rendered it valuable for cooling purposes. 
At temperatures above 212 degrees F. it is completely evaporated, 
and a decomposition into ammonia and muriatic acid occurs. It 
is used in certain packings in which iron filings are incorporated. 

Ammonium Tungstate. — A crystalline body which is very 
solubk in water and becomes covered with a white bloom or 
efflorescence on exposure to the air. Used with boracic acid, 
kauri, borax, and rubber in the production of the woodite fire- 
proof composition. 

Aniline. — An oily liquid, colorless when pure but ordi- 
narily straw color. Its specific gravity is 1.02 at 60 degrees F. 
and its boiling point 364.6 degrees F. Commercially, aniline 
is obtained by a series of chemical transformations, beginning 
with coal tar. Among the products liberated from coal tar by 
distillation is benzol. Benzol, when acted upon under suitable 
conditions with mixed nitric and sulphuric acids, is converted 
into nitrobenzol. Nitrobenzol may further be acted upon and 
chemically "reduced" to aniline oil by treatment with dilute 
hydrochloric acid in the presence of a slow feed of common cast 
iron borings, both acid and borings being in definite proportion 
to the charge of nitrobenzol to be reduced. If sold as pure 
aniline should not contain over one-half of one per cent, of 
water, and should be free of nitrobenzol. A delicate test for 
the presence of nitrobenzol in aniline oil is to shake a sample 
violently for a few minutes, and notice the color of the froth 
so produced. The merest trace of nitrobenzol present will give 
a very distinct yellow coloration. 



198 ACIDS AND ALKALIES 

In recent years the use of aniline in the manufacture of 
rubber goods has increased to large proportions. The chief 
function of aniline as a compounding ingredient is that it serves 
as a catalyzer, accelerating the combination of sulphur and rub- 
ber in the process of vulcanization. Its use is accompanied by 
a considerable degree of danger to the health of the workmen 
unless adequate measures are adopted to prevent its fumes be- 
ing inhaled or the liquid coming in contact with the skin, through 
which it is readily absorbed. 

An American process for reclaiming waste vulcanized rub- 
ber calls for its admixture with aniline oil and subsequent steam 
devulcanization. 

Aniline was used by Parkes in the manufacture of parke- 
sine. It is also a solvent for gutta-percha and in the laboratory is 
used in analytic work as a solvent for vulcanized rubber. 

The so-called aniline dyes are derivatives of aniline. 

Antimony Iodide. — A brownish- red crystalline mass, which 
yields a cinnabar-red powder. It is soluble in hot carbon bisul- 
phide. Its specific gravity is 4.39. It was used by Parkes in 
vulcanizing india rubber. 

Barium Chloride. — A white crystalline powder. Its spe- 
cific gravity is 3.05. To makers and users of sulphurets it 
affords a ready means of determining the presence of free sul- 
phuric acid, so liable to occur in these bodies and so injurious 
to rubber compounds when present. A suspected sulphuret 
should be boiled for a moment with a little distilled water, the 
water filtered off, and a drop or two of a solution of barium 
chloride added; a white cloudiness that will settle in the form 
of a white powder proves the presence of sulphuric acid and 
such a sample should be rejected. Barium chloride is a powerful 
poison. Used with size and acid resin as a shower-proof mixture. 

Bleaching Powder or Chloride of Lime is a mixture of 
the chloride and hypochlorite of lime. Industrially, its chief use 
is for bleaching purposes, dependent upon the amount of chlorine 
it contains. Commercial bleaching powder is a white powder 
with a smell of peculiar character (chlorine) and gradually be- 
coming moist on exposure to the air, while it gradually decom- 
poses and absorbs water and carbonic acid. Even in closed 



BORACIC ACID— CARBOLIC ACID 199 

vessels decomposition occurs, and sometimes so suddenly and 
with such a rise of temperature that explosions occur. Hence 
it should always be used fresh and a guarantee obtained from 
the vendors (as is customary) of the quality of the article. 
Chloride of lime is the basis of a cold-curing process known as 
Caulbry's (which see). Gutta-percha boiled in it and then mixed 
with rosin and paraffin is used in insulation. 

Boracic Acid. — This is found native in the vapor which 
arises from certain volcanic rocks, in a saline incrustation in 
volcanic craters and in combination with borax. It appears in 
the form of pure white feathery crystals of the specific gravity of 
1.43. Boracic acid is used with tungstate of ammonia, kauri, 
borax, and india rubber in the production of the woodite fire- 
proof compositions. 

Borax. — See Sodium Biborate. 

Calcium . Chloride. — A crystalline substance containing 
about 50 per cent, of water of crystallization, which is lost on 
heating to 392 degrees F. The specific gravity is 1.61, and 
that of the dried form 2.21. Its extreme attraction for water 
makes it useful in obtaining a dry atmosphere in any closed 
receptacle. Its color is white. It absorbs ammonia readily and 
will give it up again on heating. It is used in bookbinders' 
cements. 

Calcium Oxalate. — Quicklime slaked by water in which 
is oxalic acid is given this name. Used in certain gutta-percha 
compounds. 

Calcium Oxide. — See Quicklime. 

Calcium Sulphide. — Lime that has been treated with hy- 
drogen sulphide. It is an offensive smelling substance, of a 
dirty greenish-gray appearance, and is obtained in the process 
of purifying coal gas. Its specific gravity is about 2.20. It 
decomposes easily, giving off sulphureted hydrogen. It will 
absorb bisulphide of carbon and is soluble in alcohol. Its lia- 
bility to oxidize should render it of questionable use in com- 
pounding. It was used by Hancock in vulcanizing india rubber. 

Carbolic Acid, also known as phenol, is obtained chiefly 
during the destructive distillation of coal. Specific gravity 1.08. 



200 ACIDS AND ALKALIES 

The liquid is corrosive and is largely used for its antiseptic 
qualities. Carbolic acid is used as a preservative of rubber milk, 
where it is coagulated by the process some time employed by 
the Orinoco Co., in Venezuela. It has also been used in con- 
nection with a little ammonia to increase the elasticity of low- 
grade African gums, being used as a solution before the gums 
are washed. It is also used for treating fabrics, such as hose 
linings for fire and mill hose, to prevent deterioration and rot- 
ting. Used in certain fiber-made substitutes and in - mbber 
reclaiming process. 

Catechu or Cutch. — Known formerly as japan earth. 
Made from the sap of an East Indian tree, and used chiefly in 
dyeing. It is very astringent, and is soluble in water. It ap- 
pears in commerce in dark-brown irregular lumps. Contains 40 
to 50 per cent, of a peculiar tannic acid. Used in packings and 
goods made from the whaleite formulas. Johnson's artificial 
leather was made of catechu, rosin oil, linseed oil, turpentine, 
and starch, mixed with a little hot gutta-percha. A number of 
other compounds both with and without india rubber, contain 
catechu, but chiefly those which were compounded from gelatine, 
starch, and gluten. Catechu is mixed with gutta-percha in solu- 
tion in order to make it harder. 

Chloride of Lime. — See Bleaching Powder. 
Chromic Acid is not readily obtained in a free state, but 
forms many well-known salts, such as chrome yellow (lead 
chromate), for instance. Chromic acid is analogous to sul- 
phuric acid. Vulcanized rubber immersed in it at 140 degrees 
F. remained a month, and was apparently unharmed. It is also 
used in the manufacture of the substitute known as corkaline. 
Citric Acid. — An organic acid that occurs in lemons, limes, 
and other citrous fruits. It is readily soluble in water. Has 
been used in the coagulation of balata. Vulcanized rubber im- 
mersed in it at 140 degrees F. remained a month, and was ap- 
parently unharmed. 

Copper Sulphate. — Sometimes called blue or Cyprus vit- 
riol. Occurs in commerce in masses of large blue crystals hav- 
ing a specific gravity of 2.28, and containing 36 per cent, of 
water of crystallization, and a varying additional percentage of 



CREAM OF TARTAR-HYDROCHLORIC ACID 201 

entangled moisture. Heated for some time at 212 degrees F., 
all the entangled water may be driven off, together with four- 
fifths of the water of crystallization, the residue being a bluish- 
white powder. Sulphate of copper solution is used in copper 
plating iron for secure attachment of rubber by vulcanization. 

Cream of Tartar. — See Potassium Acid Tartrate. 

Cutch. — See Catechu. 

Formic Acid obtains its name from the fact that it was 
first obtained from the red ant. It is a fuming liquid with a 
pungent odor, boiling at 212 degrees F., specific gravity 1.22. 
It is now made from a mixture of starch, binoxide of manganese, 
sulphuric acid, and water. It has been suggested as an ideal 
precipitant for rubber milk. It is quite volatile, could be easily 
washed out, and would be found more beneficial to the rubber 
than many of the alkaline solutions now used. 

Hydrochloric Acid is known usually by its trade name 
of muriatic acid. It is one of the principal mineral acids and a 
common reagent in chemical analysis. Used in the arts in the 
form of a water solution, of which the strength varies from a 
specific gravity of 1.01 or 2 degrees Baume with 2.02 per cent, 
acid to 1.21 or 26 degrees Baume, with 42.85 per cent. acid. 
Each .01 increase of gravity corresponds to 1 degree Baume 
and 2.02 per cent, of acid. It is corrosive to the skin and attacks 
nearly all metals. It has no action on caoutchouc and very little 
on oxidized linseed oil if the acid be dilute. With soda it forms 
common salt and with metals it forms chloride thereof. Hydro- 
chloric acid, during the treatment of reclaimed rubber, turns 
whiting into calcium chloride. As the chloride is more soluble 
than sulphate of lime, much of it washes out during the vigor- 
ous cleansing that the rubber undergoes to remove the free acid. 
Hydrochloric acid, according to tests made by William Thomp- 
son, F.R.S., did not at all injure india rubber, although it was 
kept in it at a temperature of 140 degrees F. for a month. Con- 
centrated hydrochloric acid has but little action on gutta-percha, 
and tubing made from it is therefore largely used in chemical 
factories for running this acid from one vessel to another. 
Hydrochloric acid is used in the manufacture of synthetic rub- 
ber from isoprene. 



202 ACIDS AND ALKALIES 

Hydrogen Peroxide. — This is a powerful oxidizing agent, 
largely used as a bleaching agent, and also for neutralizing after 
chlorine bleaching. It comes in the form of a colorless liquid, 
and has a specific gravity of 1.45. Neither the alkaline nor the 
acid solutions of this reagent seems to impair vulcanized india 
rubber. In certain cases peroxide of hydrogen has been used in 
removing the bloom from rubber, which it does most effectively; 
besides, it seems to penetrate the surface of the rubber and dis- 
solve the sulphur. It also has a curious effect on colors, bright- 
ening some reds wonderfully, dulling others, and rendering 
whites much whiter. One curious effect that it has upon india 
rubber is to bring out any surface imperfections to a marked 
degree. 

Lead Acetate or Sugar of Lead. — This is used in certain 
rainproof compounds, one of which is 16 parts of compounded 
rubber, 128 parts of paraffin wax, 1 part of sugar of lead, 1 
part of alum in powder. The india rubber compound used con- 
tains no sulphur. Used also in artificial rubber and artificial 
ivory. Specific gravity 2.50. 

Lead Nitrate. — A compound of lead and nitric acid con- 
taining 62.5 per cent, of lead. Its specific gravity is 4.58. It 
crackles when heated, detonates when thrown on red hot char- 
coal, and takes fire when ground with sulphur. Its color is 
white and it is largely used in dyeing and for making chrome 
yellow (which see). It is used with gums in the production of 
shower-proof mixtures with sugar of lead and alum. 

Liquor of Flint. — See Sodium Silicate. 

Mimo-tannic Acid. — See Catechu. 

Muriate of Ammonia. — See Ammonium Chloride. 

Muriatic Acid. — See Hydrochloric Acid. 

Nitric Acid. — A strongly acid liquid consisting of an 
aqueous solution of the pure acid. Its action is strongly oxi- 
dizing. Tin and powdered antimony are rapidly converted into 
their oxides, while turpentine, if poured into the strong acid, 
is attacked with almost explosive violence with the evolution of 
light and heat. Straw or sawdust may become ignited if im- 
pregnated with this acid. Cotton wool is converted by it into 
gun cotton. Rubber immersed in nitric acid at a temperature 



NUT-GALL— OXALIC ACID 203 

of 140 degrees F., was injured in a few hours, and in a few 
days its elasticity was destroyed, while at the end of the month 
it was reduced to a pulp. Nitric acid attacks gutta-percha very 
powerfully, and evolves suffocating fumes of a deep red color, 
the gum meanwhile being reduced to a pasty mass which after- 
wards dries and becomes very brittle. According to H. L. Terry, 
nitric acid of any strength has a very deleterious effect upon 
india rubber, the action of the fuming acid being to form im- 
mediately an oxidized body of a resinous nature. He holds, 
therefore, that the weaker acid also injures the india rubber, al- 
though of course in a less degree. Nitric acid is used in the 
treatment of leather cuttings to reduce them to a glutinous mass 
before being mixed with india rubber, and is also used in mak- 
ing certain substitutes. 

Nut-gall. — An excrescence formed on the leaves of a spe- 
cies of oak called Quercus infectonia. It is used in the arts for 
the sake of the tannic acid it contains. There are three varieties 
in commerce — green, white and black. The black and the green 
are preferred. Those grown in warm countries are the best. 
Aleppo galls contain from 60 to 66 per cent, of tannic acid. 
There is a variety of nut-gall known as Chinese, imported from 
Japan, China, and Natal. The gall is somewhat bean-shaped 
or is covered with a yellow-gray felt. It contains from 60 to 
70 per cent, of tannic acid. Nut-gall is used in certain places 
instead of tannin. 

Oil of Vitriol. — See Sulphuric Acid. 

Oleic Acid. — An acid found in animal and vegetable oils, 
such as olive oil, sperm oil, etc. Specific gravity .890. It has 
been used in certain substitutes for hard rubber, like voltit, and 
by Hunt for recovering waste vulcanized rubber under heat, 
methylated spirit being added later to precipitate the rubber, 
which was then washed in a weak caustic soda. 

Oxalic Acid occurs in transparent, colorless prisms, spe- 
cific gravity 1.63, soluble in both cold and hot water. It is 
produced by either the action of potassium hydrate, or of nitric 
acid upon most organic compounds. It is very poisonous. 
Gutta-percha was cleansed by Lorimer's process by boiling in 
water mixed with this acid. 



204 ACIDS AND ALKALIES 

Phenol. — See Carbolic Acid. 

Potassium Acid Tartrate or Cream of Tartar. — A white 
crystalline substance with an acid taste, a very common in- 
gredient in baking powders; also called potassium bitartrate. 
Specific gravity 1.96. It is made from purified tartar, or argol. 
It is used in artificial ivory made from resins in solution. 

Potassium Arsenate. — A very soluble compound of arse- 
nic with potash forming what is known as Fowler's solution. 
In the dry state it is a white powder soluble in alcohol up to 
4 per cent. Potassium arsenate was used by Forster, in his 
earliest experiments, to vulcanize partially a compound made 
up of india rubber and shellac. 

Potassium Bichromate. — The principal compound of 
chromium, which occurs in the form of orange-red crystals, 
specific gravity 2.69. It is soluble in water and is largely used 
in dyeing. Mixed with sulphuric acid, it is used in bleaching 
palm oil and other fats. Bichromate of potassium is used in 
hardening the compound known as elastic glue; also used in 
Christia gums. 

Potassium Bisulphate. — A white powder obtained as a 
by-product in chemical manufacturing. Soluble in twice its 
weight in cold water, and in half of its weight in boiling water. 
It contains sulphuric acid so loosely held in combination that it 
is driven off upon heating. Its specific gravity is 2.16. 

Potassium Carbonate or Potash. — This substance is 
usually met with commercially in small, colorless crystals. It 
is prepared in a variety of ways and forms, and is the basis 
from which is derived what is called caustic potash. Pearl ash 
is a crude form of potash mixed with the caustic variety and 
a sulphuret of potassium. Used in certain proofing compounds 
where low heat is required for cure. It was used by Charles 
Hancock, mixed with water in a bath, to improve the quality 
of gutta-percha. He found, by boiling the gutta-percha in such 
a bath for an hour, that it did not oxidize in the open air as 
badly. An old-fashioned process for treating unvulcanized 
thread was to steep it in a hot solution of carbonate of potash, 
which greatly increased its strength. See Caustic Potash. 

Potassium Cyanide. — A white crystalline substance, very 



POTASSIUM CYANIDE— QUICKLIME 205 

poisonous. Specific gravity 1.54. It is very easily decomposed, 
even on exposure to the air, absorbing carbonic acid and yield- 
ing prussic acid, which gives the salt its peculiar smell of peach 
kernels. The vapors thus given off are very poisonous. Cy- 
anide of potassium was used by Brooman "to give clearness 
to the gum which was made from the ground vulcanized rubber, 
which had been treated with alkalies and acids to remove sulphur 
and adulterants." 

Potassium Hydroxide or Caustic Potash. — As occurring 
in commerce, this is a white solid substance of the specific gravity 
of about 2.5. It is hard and brittle, and very destructive to 
animal and vegetable substances. It rapidly takes up water 
from the air, and may be used to obtain a dry atmosphere in 
a confined vessel. It is also a greedy absorbent of carbonic 
acid, becoming converted into the carbonate thereby. Solutions 
of potash should be clarified by allowing impurities to subside. 
Alcoholic caustic potash solution is used in analysis of vulcan- 
ized india rubber and was introduced by Henrichs, particularly 
to separate india rubber from india rubber substitute. Caustic 
potash is mixed with flowers of sulphur for boiling drawing 
rolls, the potash making the rubber more solid, while the sulphur 
gives a peculiar surface, making it better for drawing. Used in 
water solution to remove bloom from cured rubber. It is also 
used in certain substitutes for hard rubber like voltit. Caustic 
potash was early used in extracting the sulphur from ground 
vulcanized rubber. 

Potassium Permanganate occurs in dark red prismatic 
crystals of greenish color which, when dissolved in water, give 
a purple red. It is a decided oxidizer, and is used as a disinfec- 
tant. It is also called chameleon mineral. Used in certain arti- 
ficial leathers. Its specific gravity is 2.71. 

Quicklime is the impure oxide of calcium obtained by 
burning chalk, marble, or limestone, or any carbonate of cal- 
cium. Its well-known attraction for water renders it unstable 
but also valuable where drying qualities are desired. Specific 
gravity about 3.30. Blizzard claimed to be able to make a per- 
fectly transparent rubber by treating it with soda and water, 
in which was a little quicklime. 



206 ACIDS AND ALKALIES 

Reclaiming Salt, — An alkaline composition made in Ger- 
many and used chiefly in the reclaiming of red and light-colored 
rubber waste. 

Rennet is made from the inner lining of the true stomach 
of the sucking calf and gets its value from the gastric juice 
contained therein. The membrane, after treatment, is salted 
and stretched out to dry. It is advised in the Vaughn process 
for coagulating balata. 

Sal Ammoniac. — See Ammonium Chloride. 

Saleratus. — See Sodium Carbonate. 

Salicylic Acid is obtained from the creeping plant known 
as wintergreen. It is prepared from the oil of wintergreen 
(oil of Gaultheria), which is distilled in large quantities in 
Luzerne county, Pennsylvania. It is also prepared synthetically ; 
specific gravity 1.44. It is soluble in the following proportions: 
1 part of the acid dissolves in 450 parts of water, or 2.4 of 
alcohol. It melts at 312 degrees to 314 degrees F. Salicylic 
acid was used in an artificial leather compound for reducing 
leather dust to a paste, after which it was mixed with glue under 
heat, and treated with an alkaline solution. 

Sal Soda. — See Sodium Carbonate. 

Salt. — See Sodium Chloride. 

Saltpeter is niter or potassium nitrate. It is a white 
crystalline substance having a saline taste, specific gravity 2.08, 
and is a very strong oxidizer. It is used in the manufacture of 
artificial elaterite. In Gridley's process for recovering rubber, 
by exposing it to flame, saltpeter was added to remove the smell. 

Silicon Fluoride is a colorless gas. What is used in the 
arts is a solution in water, forming a very acid fuming liquid. 
It is easily decomposed and may be used for etching glass if 
allowed to evaporate upon it under heat. It is prepared from 
flints or silica in some such form as sand or powdered glass. Used 
in treating meerschaum and paper pulp which, combined with 
certain resins, forms an artificial ivory. 

Soap. — Various kinds of soap are used in rubber manufac- 
ture. Pure Castile soap, for instance, is dissolved in rain water 



SOAPS—SODIUM BIBORATE 207 

and made into a soft soap that is used to "slick" molds that 
the rubber, during vulcanization, may not adhere to them. Some 
manufacturers use by preference white soda soap made from 
caustic soda and olive oil. Resin soaps are also used in certain 
shower-proof compounds. A further use for soap is in the 
manufacture of water varnishes for luster coats and blankets. 
A soap compound for wagon covers is made of 50 pounds of 
soap dissolved in 15 gallons of water, heated to 250 degrees F., 
to which is added 25 pounds of sulphide of zinc. A half pint 
of rubber dissolved in olive oil by heat is added to each gallon 
of the above mixture. Whiting, lampblack, or coloring matters 
may be added. Vulcanized rubber, beeswax, rosin oil, argil- 
laceous earth, and alkaline soap form the basis of Sorel's sub- 
stitute for rubber. 

Soap Bark. — Bark of a Venezuelan tree, Pithecolobium 
bigeminum. Its water extract is used to "slick" molds. 
Soda. — See Sodium Carbonate. 

Sodium Biborate or Borax. — Sometimes also called tin- 
cal; a compound of soda and boracic acid. The purified com- 
mercial article contains about 4 per cent, of water of crystal- 
lization and is usually in the form of large odorless crystals, or 
a white powder obtained by grinding. The crystalline form 
has a specific gravity of 1.69. Borax is quite soluble in water, 
but not in alcohol or any of the common solvents for rubber. 
At a moderate heat borax loses water, and separates as a spongy 
mass called calcined borax, while at a higher heat it melts into 
borax glass. Immense deposits of it are found in western United 
States, and it is also found in India, Hungary, and other parts 
of the world. A good waterproof cement is made of a mixture 
of borax and shellac boiled in water. Borax, or a solution of 
biborate of sodium, has the property of dissolving many resins. 
Lascelles-Scott describes the manner in which an emulsion of 
rubber may be preserved by a borax solution. To a solution 
of rubber, in any one of the common solvents, a small portion 
of alcohol is added. This is mixed with a 2-5th saturated solu- 
tion of borax, previously heated from 120 degrees to 14Q degrees 
F. This is agitated until the temperature has cooled to the 
temperature of the air. From Zy 2 per cent, to A l / 2 per cent. 



208 ACIDS AND ALKALIES 

of india rubber should be present in the fluid when finished. A 
higher strength quickly separates and sometimes causes the en- 
tire quantity to coagulate. Madagascar or Sierra Leone rubbers 
are advised for borax solutions. Solutions of borated rubber 
are adapted for waterproofing and for preserving mats, marine 
bedding, etc. Borax is also advised for preserving rubber milk 
from coagulation. It is also an important ingredient in the 
water varnishes used for luster finish, for surface coats, army 
blankets, etc. ; is used in waterproofing compounds composed of 
rubber, boracic acid, kauri, tungstate of ammonia; mixed with 
gutta-percha and shellac, it was used by Hancock as an insulat- 
ing material. 

Sodium Bisulphite. — Used for bleaching plantation rubber 
during coagulation. 

Sodium Carbonate. — Also called sal soda, washing soda. 
Prepared from cryolite, salt, etc. Its specific gravity is 1.45, 
when crystallized. The crystalline form contains 64 per cent, 
of water of crystallization, of which one-half is driven off by 
gentle heating. It is found in the ashes of many plants, is pro- 
duced artificially in large quantities from common salt, and is 
used as an alkaline agent in many chemical industries. India 
rubber, burnt umber, japan, and a coloring matter are mixed 
with a certain proportion of sal soda for a waterproofing com- 
position. Under the common name saleratus, carbonate of soda 
is used as follows : Instead of sunning surface goods, like rub- 
ber coats and blankets, they are often brushed over with a mix- 
ture of saleratus and powdered charcoal immediately after the 
stock leaves the calender. Sometimes the saleratus is left out 
and only charcoal is used. 

Sodium Chloride (or common salt) has a specific gravity 
of 2.3. It is a very stable compound, soluble in water at the 
ordinary temperature to the extent of 36 per cent., and at the 
boiling point, of 39 per cent. At the freezing point water will 
take up Sy 2 per cent, of common salt. It is used in coagulating 
many of the rubber latexes. Salt is viewed with considerable 
distrust by ordinary manipulators of rubber. Payne, however, 
treated gutta-percha scraps by boiling water, salt, and oil of vit- 
riol, to get a solution to which he added other gums and metallic 



SODIUM HYDROXIDE— SODIUM PHOSPHATE 209 

oxides to get a waterproofing mixture. Cooley made artificial 
leather of gutta-percha dissolved in rosin oil, and added 25 per 
cent, or more salt, to which he added starch or other saccharine 
substances. Salt solution is used in washing the compound 
known as tremenol. It is also used in shower-proofing com- 
pounds, in connection with paraffin and sulphuric acid. 

Sodium Hydroxide or Caustic Soda. — Specific gravity 
2.13. The chief use of this, in the manufacture of rubber goods, 
is in the dissolving of sulphur that is formed on the surface of 
goods, and which is known as bloom. According to H. L. Terry, 
F.I.C., the bulk of the alkali supplied to rubber manufacturers 
in England is used in removing the sulphur from elastic thread. 
It is also used in treating tobacco pouches, fine sheet articles, 
and blacks, reds, or maroons, that should have a good clear 
color. The boiling of rubber goods is usually done in wooden 
tanks in which steam can be passed, and sometimes in slate tanks, 
as iron is attacked by the alkali. On good grades of rubber, 
caustic soda has no action at all. Where a large quantity of 
resin is present, however, it may dissolve a part of it, forming 
resinate of soda. Heavily compounded rubbers, whether they 
contain substitutes, gums, or compounds, unless they are abso- 
lutely inert, are also liable to be attacked through the dissolu- 
tion of their ingredients. Camille describes a process whereby 
shoddy is treated with a solution of carbonate of soda in devul- 
canization. In this, the rubber is boiled several hours in a solu- 
tion of caustic soda, the result being that it will sheet when the 
process is completed. Rostaing purified gutta-percha by boiling 
in caustic soda, or in a mixture of caustic soda and potash in 
water. 

The largest use for caustic soda in the rubber industry is 
found in the reclaiming of waste rubber by the alkali processes. 

Sodium Hyposulphite. — A one per cent, solution is used 
for removing traces of chlorine where its presence is suspected in 
india rubber. 

Sodium Phosphate. — A crystalline colorless substance con- 
taining 60 per cent, of water, which is given up on heating to 
248 degrees F., leaving behind a dry mass. The commercial 
article frequently contains sulphate of soda as an impurity. The 



210 ACIDS AND ALKALIES 

crystals have a specific gravity of 1.5, melt at 95 degrees F., 
and are readily soluble in water. By long drying at 113 degrees 
F., the water of crystallization may be entirely driven off. The 
presence of this material is called for in a certain compound for 
dental vulcanite, where it is incorporated with rubber, sulphur, 
and phosphate of lime, the idea being that less sulphur is re- 
quired for vulcanization than in the ordinary compounds. 

Sodium Silicate. — See Soluble Glass. 

Sodium Sulphate occurs commercially in colorless crystals 
which deteriorate in contact with the air, and hence should be 
kept in well-closed vessels. It contains a very large amount — 
nearly 60 per cent. — of water of crystallization, which is yielded 
on heating to 302 degrees F. Its reaction is alkaline. Sulphate 
of soda was used by Hancock in vulcanizing gutta-percha. Its 
specific gravity is 1.48. 

Sodium Tungstate. — Prepared commercially from wolfram 
ore and soda ash; usually contains about 14 per cent, water of 
crystallization; and is in the form of colorless crystals. Mixed 
with a solvent such as methylated ether, it is added to soluble 
gun cotton, castor oil, and gum copal, forming a substitute for 
india rubber. Specific gravity 3.256. 

Soluble Glass (known also as waterglass) is a silicate of 
soda or potash. It is usually sold in solutions of varying density, 
the commonest being 33 degrees and 66 degrees, by which is 
meant that the solution contains either one-third or two-thirds 
solid waterglass. Acids readily precipitate the silica from these 
solutions as a gelatinous mass. It is used in certain shower-proof 
compounds and in compounds of the algin type. 

Sulphuric Acid (called also oil of vitriol), when pure, is 
a colorless, heavy, oily liquid. It is very corrosive, and has a 
great attraction for water; hence wood and other organic bodies 
are charred in the heat evolved by it depriving them of their 
water. The specific gravity of the commercial acid is usually 
about 1.83, or 66 degrees Baume, containing 94 per cent, of 
acid. Sulphuric acid is used in the coagulation of Madagascar 
rubber. The Orinoco Co., in Venezuela, are also said to have 
coagulated india rubber by mixing the milk of the Hevea with 
sulphuric and carbolic acid. Commercial sulphuric acid is said 



TANNIN— TARTARIC ACID 211 

to coagulate 55 times its volume of gum, while the carbolic acid 
acts as an antiseptic in the juice, improving its keeping qualities. 
It is a question whether rubber treated this way is as good as 
that obtained by the smoking process. Rubber immersed in sul- 
phuric acid at 140 degrees F. remained a month and came out 
stronger, apparently, than when it went in. Sulphuric acid is 
used in paste blacking, mixed with bone black, vinegar, molasses, 
and caoutchouc oil. Concentrated sulphuric acid colors gutta- 
percha brown, throwing off at the same time sulphurous acid 
fumes. Nevertheless, a paste of this acid and charcoal was added 
by Hancock to gutta-percha to make it pliable. Sulphuric acid 
may be expected to attack vulcanized rubber compounds in 
which there are large proportions of chalk, lead, or zinc oxides. 
Sulphuric acid is very largely used in destroying the fiber found 
in ground waste rubber; indeed it is the basis of what is known 
as the acid reclaiming process. When thus used the acid turns 
whiting into sulphate of lime. 

Tannic Acid. — See Tannin. 

Tannin includes a number of substances, some of which 
are crystalline and others amorphous, having marked astringent 
properties and no smell. Tannins are acid, soluble in water and 
alcohol, and yield precipitates with most metallic oxides. Tannin 
is the active principle of oak bark, hemlock bark, catechu, and 
many other materials commonly used for tanning hides. Pure 
tannin is a light powder of a yellow-greenish hue, specific gravity 
1-.10. Its solution precipitates glue. It is used with sulphate of 
alumina, waterglass, and glue in shower-proofing. Tannin has 
been claimed to be injurious to rubber, the reason being that 
rubber thread used in gorings is often destroyed at points close 
to its junction with the leather. It is more likely, however, that 
it is the oil in the leather that effects the destruction. Tannin 
was largely employed by Austin G. Day in many of his "kerite" 
compounds with excellent effect. It is also used in the manufac- 
ture of certain puncture fluids, together with glue and glycerine. 

Tartaric Acid is found usually in the form of transparent 
colorless prisms, which have an agreeable acid taste, are not 
affected by the action of the atmosphere, and are soluble in either 
alcohol or water. Specific gravity 1.66 to 1.76. This acid is 



212 ACIDS AND ALKALIES 

very abundant in the vegetable kingdom, being found in many 
fruits. Used under Vaughn's patent in coagulating balata. Vul- 
canized rubber immersed in tartaric acid at 140 degrees F. re- 
mained a month, and was apparently unharmed. 

Tungstic Acid is derived chiefly from wolfram, which is a 
tungstate of iron and manganese. Tungstic acid is analogous to 
sulphuric and chromic acid. It has been used in connection with 
paraffin, gelatine, and metallic oxides in proofing compounds. 

Zinc Chloride was known formerly as butter of zinc. It 
is formed by burning zinc in chlorine gas, or by dissolving it in 
hydrochloric acid, the solution being evaporated. Its specific 
gravity is 2.75. The anhydrous form is a whitish-gray mass 
which readily fuses, and can be sublimed at a high temperature. 
It deliquesces on exposure to the air, and is readily soluble in 
Water, acting in a concentrated state as a powerful' caustic. One 
of the best processes ever known for reducing the fiber in re- 
covering rubber was that in which this substance was employed 
instead of acid. A boiling solution of chloride of zinc was used 
in deodorizing by Brockedon, who also mixed it with gutta- 
percha, adding sulphur and vulcanizing the gum. Hancock also 
subjected gutta-percha for a moment or two to binoxide of nitro- 
gen, then immersing it in a boiling solution of chloride of zinc, 
which he claimed greatly improved its quality. 

Zinc Iodide. — A very unstable substance. A white granular 
powder, odorless. Chiefly used in medicine. It was used by 
Hancock to assist in the vulcanization of india rubber. Specific 
gravity 4.70. 



CHAPTER XII. 

VEGETABLE, MINERAL, AND ANIMAL OILS USED IN 
RUBBER COMPOUNDS AND SOLUTIONS. 

The use of oils in rubber manufacture has kept pace fully 
with the use of gums, substitutes, and reclaimed rubber. The 
addition of earthy or metallic or vegetable ingredients in dry 
mixing has rendered many a good rubber somewhat intractable — 
a fault which the right oil has often rectified. As a rule, vege- 
table oils are chosen, as they are rarely harmful to the gum. 
Many mineral oils are also freely incorporated in certain com- 
pounds. Animal oils have always been viewed with more or less 
suspicion, however, and with good reason, for manufacturers 
have constantly before them rubber goods that have lost their 
life and elasticity through contact with lubricants made of such 
oils and fats. Nevertheless certain of them may be and are 
used. The essential or volatile oils are used to a certain extent 
in rubber manufacture. These oils, as a rule, give the peculiar 
odors of plants from which they are derived. Their use in rub- 
ber is to impart to it a pleasing odor. 

Aluminum Lanolate. — This is a product precipitated from 
French wool grease, made by adding a solution of alum. It is 
dissolved in mineral oil, forming a jelly-like mass which is said 
to compound readily with either india rubber or gutta-percha, 
and is soluble in any of their solvents. It is possible that this 
may have both softening and preservative influences on india 
rubber, as is claimed, but it should be used with considerable 
caution. 

Blown Oils. — These are prepared by heating fixed vege- 
table oils in a jacketed kettle and blowing a current of air through 
the fluid. Under this treatment, oils become much more dense, 
viscous, or even solid by combining with oxygen. In many 
physical aspects they resemble castor oil, but differ in that they 
<:an be mixed with mineral oils and as a rule are not easily soluble 

213 



214 OILS IN RUBBER COMPOUNDS 

in alcohol. Blown oils made from linseed oil, rape oil, poppyseed 
oil, and cottonseed oil are sometimes used in the manufacture 
of rubber substitutes instead of the raw oils. Known also as 
thickened oils, base oils, soluble castor oil, etc. 

Camphor Oil. — A liquid of a light reddish-brown with a 
yellowish tint, and a strong camphor odor. Its specific gravity 
is 0.94. The Japanese oil varies in color from colorless through 
pale straw and yellow, to black, and has a specific gravity of 0.898 
for the colorless to 0.99 for the very dark. This oil is used in 
the manufacture of celluloid varnishes, paints, lampblacks, etc. 
It is used also as an adulterant for such oils as sassafras oil. 
It is one of the best solvents for resins, and dissolves 46 per 
cent, of rosin, 9 per cent, copal, and 35 per cent, of mastic. 

Caoutchouc Oil. — Made by digesting 55 parts of india 
rubber in 450 parts of linseed oil. The principal large use for 
this oil is in Germany, particularly in the army, for coating 
various articles to prevent their rusting. The following sub- 
stances are found in oil of caoutchouc: eupoine, butylene, 
caoutchoucine, isoprene, caoutchine, and heveene. 

Castor Oil. — A colorless or pale greenish transparent oil, 
very viscous and thickening on exposure to the air. It has a 
higher specific gravity than any other known natural fatty oil — 
0.958. It is adulterated frequently with resin oil and rape, lin- 
seed, and cottonseed oils, especially the "blown" variety. Used 
in cheap proofings without rubber with kauri gum; also in col- 
lodion and rubber proofing. It is used in the production of 
substitutes like gum fibrine, and also with chloride of sulphur 
in producing amber-colored and white substitutes. 

Cholesterin. — See Lanichol. 

Cod Oil or Cod-Liver Oil is obtained from the livers of 
codfish. Newfoundland and Norway are the principal manu- 
facturing points. The finest is a very pale, clear, golden yellow, 
the color deepening to a brown in the second and third grades. 
Its specific gravity is 0.923 to 0.929. One part of oil is soluble 
in from 40 to 20 parts cold alcohol, or 30 to 17 parts hot alcohol. 
The lower grades are the more soluble. It is much adulterated. 
Is compounded with india rubber, beeswax, linseed oil, litharge, 



COLZA OIL—EUCALIPTIA 215 

and asphalt as a waterproofing for leather and with india rub- 
ber, beeswax, and turpentine as a dressing for hides. 

Colza Oil. — See Rapeseed Oil. 

Consolidated Oil. — See Stearine. 

Corn Oil or Maize Oil. — Made from the seed of Indian 
corn, the plant known botanically as Zea mays. There are two 
processes of manufacture : ( 1 ) in which the seed germ is pressed 
before it is used for the manufacture of starch, which produces 
oil of a golden yellow color, and (2) where it is recovered from 
the residue of the fermentation vats where the corn has been 
used in the production of alcohol. This oil dissolves sparingly 
in alcohol, but very readily in acetone. The oil is almost with- 
out drying powers. Neither boiling nor the addition of lead 
when boiling gives it definite drying properties. If it is heated, 
however, and a current of air passed through it, and manganese 
borate mingled with it, it dries after a fashion. It is largely 
used at present in the manufacture of what are known as corn- 
oil substitutes. Specific gravity 0.921-0.928. 

Cottonseed Oil is expressed from the seeds of the cotton 
plant, usually the Gossypium herbaceum. The crude is of a ruby- 
red, almost black color. The refined is pale yellow and possesses 
a pleasant, nutty taste. The specific gravity is about 0.930. It 
is a semi-drying oil, and is rarely adulterated except when lin- 
seed oil is very cheap. On standing it deposits stearine in waxy 
flakes. It is much used in making substitutes for rubber. It is 
also used in the production of artificial elaterite, and with paraf- 
fin oil for canvas proofing. It is converted into "blown" oil. 

Creosote Oil is a distillate from wood tar. Specific grav- 
ity 1.04-1.09. It is an oily liquid with a smoky odor, and is 
antiseptic. It should be colorless but is usually yellow or brown, 
due to impurities or to exposure. The best is made from the 
beech. A similar oil is distilled from coal tar. It has been used 
as a preservative to coat the fabric of which cotton hose is made ; 
with india rubber and sulphur it has also formed an insulating 
compound for telegraph wires. 

Eucaliptia. — A fragrant, refreshing volatile oil. It is pre- 
pared from eucalyptus oil. 



216 OILS IN RUBBER COMPOUNDS 

Eucalyptus Oil. — An aromatic oil found in the leaves of 
the Eucalyptus globulus in Australia. The odor of the oil is 
extremely pleasant, smelling not unlike oil of verbena. Its spe- 
cific gravity is about 0.900. It has great solvent power on all 
resins and gums, including india rubber and gutta-percha. With 
the addition of a little methylated spirit it will dissolve even 
kauri gum, cold. It is also used in dissolving asphalt for photo- 
graph varnish. 

Fish Oil. — Obtained from all parts of the bodies of com- 
mon fish by boiling. Fish whose livers yield oil commercially 
do not give fish oil, and those bodies that yield oil, do not give 
liver oils. Principally prepared from menhaden. Its specific 
gravity varies between .915 and .930. Fish oil is used in the 
manufacture of the substitute known as volenite. It is used, 
however, only as a vehicle for carrying resin into the fiber, be- 
ing afterwards wholly removed. 

French Wool Grease. — See Lanoline. 

Glycerine. — A clear, viscous liquid without odor. When 
pure it has a specific gravity of 1.26. The glycerine of commerce 
is a by-product of soap manufacture. When fat (glycerine 
stearate) is heated with caustic alkali and water the alkali dis- 
engages and takes the place of the glycerine in the combination, 
forming soap or stearate of the alkali, which separates out as 
a solid, leaving the glycerine free in watery solution, from which 
it is recoverable. Glycerine is not acted upon by oxygen, and 
therefore more closely resembles mineral oils (such as are used 
in rubber mixing) than it does the drying oils that go to make 
up substitutes. It has absolutely no solvent action on rubber. 

A recent German patent calls for the addition of glycerine 
because of its oil-resisting qualities. In the compound used are 
6 pounds of rubber, and 1 pound of glycerine, together with 
whiting, litharge, and sulphur. A solution of glycerine and 
alkaline fluid is also used as a cleaning and polishing medium in 
the last stages of the manufacture of certain cut-sheet goods. 
Glycerine, combined with gelatine and borax, has been used as a 
wash for both black and red rubber surfaces. 

Glycerine was the basis of a well-known deodorizing com- 
position for india rubber, the other ingredients being of an alka- 



HYDROLENE— JAPAN WAX 217 

line nature. A bath of glycerine has also been used for experi- 
mental work in vulcanizing india rubber, and also for rubber 
stamp making. In this kind of work, the mold and its contents 
are immersed in the glycerine so that the liquid just covers the 
top of the mold; heat is then applied to the glycerine, and the 
mold in turn becomes hot and the rubber vulcanizes. It is also 
used to a certain extent in good grades of white rubber, as it 
gives a softened effect to the compound. Glycerine, in connec- 
tion with glue, gelatine, molasses, and tannin, is used in the 
manufacture of puncture fluids for tires. It is also used in 
clothing compounds, and in cellulose products, like pegamoid. 
Used in rubber, a little of it increases the resiliency of the product. 

Hydrolene. — A rubber assistant used in connection with the 
reclaiming of rubber, and also rubber compounding. It would 
seem to be a petroleum product, and in rubber reclaiming is used 
instead of stock oil or residuum. 

Kerosene. — An illuminating oil of the paraffin series of 
hydrocarbons. Its specific gravity varies from 0.78 to 0.81. It 
has a flashing point (open cup test) from 90 to 110 degrees F., 
and includes all the intermediate distillates from crude petroleum 
of specific gravity 0.76 to 0.83. Its color should be water white. 
In rubber work it is useful to impart and retain softness in 
stocks in which it is desirable to retain resiliency, as in certain 
solid playing balls. Also it is very freely used in the manipu- 
lation of high-grade compositions used in hard rubber manufac- 
ture. Calender rolls, mill rolls and zinc surfaces are kept coated 
with a film of kerosene to give the hard rubber composition a 
perfect surface, exclude air and lubricate the molds and dies. 
Its use for the purpose of effectually suppressing the loss and 
nuisance occasioned by floating lampblack in rubber mixing, has 
been patented recently. The color is agglomerated by damping 
and mixing with kerosene before addition to the general batch. 

Japan Wax. — A white or pale-yellow vegetable fat, with a 
specific gravity of 0.97 to 0.98. It is used in wax matches, can- 
dles, and for adulterating beeswax. A special use for it, that 
has arisen within the last few years, is in the manufacture of 
cravenette cloths. Most of this vegetable wax is derived from 
the fruit kernels of a tree peculiar to Japan, which begins to 



218 OILS IN RUBBER COMPOUNDS 

fruit at about 15 years, and sometimes bears heavily when it is 
over 100 years old. It reaches a height of 20 to 25 feet, and 
produces from 30 to 150 pounds of nuts annually. The best wax 
is made from nuts that have been kept over the winter, and gen- 
erally speaking, the quality of the product improves with the 
age of the nut. The wax is extracted by crushing and steaming 
the nuts, and then subjecting the mass to pressure. A second 
wax is secured by re-pressing. One workman can handle about 
150 pounds of raw mass in a day, and this produces about 16 
pounds of wax. 

The crude wax is cast into round molds of a little more 
than a pound each. It is next refined, the process used being a 
traditional one and peculiar to Japan. It is mixed with wood 
or charcoal, ash and water, thoroughly boiled, and dropped into 
cold water, so as to form what are called wax flowers. These 
are taken out and exposed to the sun for about 20 days, when 
the process of boiling, making the flowers, and sunning is re- 
peated. The wax is then boiled a third time, and the best qual- 
ity taken off the top while it is in a molten condition. Recently 
improved methods have begun to come into use, and the crude 
wax is treated with an alkaline solution. 

Lallemantia Oil is obtained from the seeds of the Lalle- 
mantia iberica, a. plant cultivated in Russia. This is one of the 
best drying oils, being said to surpass even linseed oil, but its 
chief use is for illuminating purposes. In Europe it is said to 
have been used instead of linseed oil in rubber substitutes. 

Lanichol. — A product of lanolin (which see), made from 
the oil of sheep's wool. It combines with gutta-percha and india 
rubber in any proportion to a perfectly homogeneous mass. This 
grease does not oxidize and is wholly antiseptic. It has no smell, 
and is impervious to the action of alkalies or to dilute sulphuric 
acid. It is said that, used in connection with gutta-percha, the 
melting point is considerably raised, while it does not diminish 
the insulating property. An insulating compound given is 50 
parts by weight of gutta-percha, 30 parts of india rubber, 20 
parts lanichol. The inventor claims that it renders gutta-percha 
less liable to oxidation, improves its elasticity and tenacity, and 



LANOLIN— LEMON OIL 219 

diminishes its liability to become sticky. Patented in the United 
States and Great Britain by Robert Hutchinson. 

Lanolin is also known as wool grease, recovered grease, 
and brown grease. It is the natural grease found in sheep's wool 
and recovered from it while the raw wool is being prepared for 
spinning. A similar grease, made from scoured woven goods, is 
known as Yorkshire grease. It is a thick yellow or brown 
offensive-smelling greasy paste. Commercial lanolin is lighter 
colored and consists of about 80 per cent, of pure wool fat and 
20 per cent, of water. It possesses in a remarkable degree the 
property of taking up water without losing its vaseline-like con- 
sistency. 

Lanolin, mixed with india rubber, works up into an exceed- 
ingly sticky mass, and is used as a medicinal plaster. It is said 
that, while it possesses the adhesive properties of the regular 
plaster, lanolin takes up the medicament, and while very sticky 
can be readily removed from the skin. It is used for the pur- 
pose of softening india rubber, and was advised for use in tires, 
as it was said to soften the compound, and to keep the tire from 
decay, and from consequent surface cracking. It was also said 
to be used in boot and shoe work. 

Lard Oil is prepared by the cold pressing of lard, which is 
the fat of the hog. It is a colorless, limpid liquid, although 
poorer grades are brown. Its specific gravity is 0.915. It is 
frequently adulterated with rapeseed oil and cottonseed oil. 
Lard oil, mixed with powdered pumice stone into a thick paste, 
is used for polishing hard rubber. 

Lavender Oil has no perfume when new, but develops it 
on being exposed to the air. It is distilled from the flowers of 
the Lavandula vera, and is used sometimes to deodorize rubber 
goods. Specific gravity 0.875-0.910. 

Lemon Oil is obtained from fresh lemon peel. A very 
volatile yellow or colorless oil ; specific gravity 0.858 ; soluble in 
bisulphide of carbon, and absolute alcohol ; often adulterated with 
fixed oils and alcohol; dissolves sulphur, phosphorus, resin, and 
fats; used to deodorize certain proofing compounds. Cologne 
sometimes takes its place. 



220 OILS IN RUBBER COMPOUNDS 

Linseed Oil is pressed from the seeds of the flax plant 
(Linum usitatissimum) , grown chiefly in India, Russia, and 
Argentina. The trade recognizes two qualities of Russian seed — 
yielding the Black Sea linseed oil, and the Baltic linseed oil — 
while that coming from India is known as East India oil. Of 
these, the Baltic is the best, and the East Indian the poorest in 
quality. The two lower grades are not up in quality, for the 
reason that the Black Sea seed contains a certain amount of hemp 
seed, while that from India is usually mixed with rape, cameline, 
and mustard seeds. The oil which is expressed from these seeds 
is of a golden yellow color, with a peculiar taste and odor. Spe- 
cific gravity 0.935. Linseed oil becomes easily rancid in the 
open air, but when spread in thin films dries into an insoluble 
substance which has been called linoxyn. Linseed oil is adul- 
terated sometimes by fish or mineral oils, and by resin oils. Old 
tanked linseed oil is used in the preparation of what is known 
as boiled oil; that is, it is concentrated by heat at a high tem- 
perature that it may more rapidly dry when used in varnish. 
This drying process is hastened by the addition of manganese 
dioxide, litharge, etc. Boiled linseed oil is much darker than raw 
oil, having a brown-red shade. It is also much more viscous and 
has a higher specific gravity. Boiled oil is adulterated in the 
same manner as is raw linseed oil, the adulterants being resin 
oils, resin, and mineral oils. 

In rubber compounding linseed oil is very often used. A 
very simple formula for waterproofing canvas is india rubber, 
litharge, sulphur, and linseed oil. It is also used in rubber var- 
nishes, to a certain extent in molded goods, and quite largely in 
hard rubber compounding. It is the basis of a great many of 
the sulphurized or vulcanized oil substitutes. Linseed oil that 
is intended for mixing in linoleum is exposed to the air until it 
is thoroughly oxidized. In this state it is insoluble in alcohol, 
chloroform, ether, and ordinary solvents. 

Lithographic Varnish is obtained by boiling linseed oil at 
a temperature higher than that at which boiled oil is prepared, 
nor are dryers added during the boiling. It is a perfectly clear, 
transparent substance, the best quality being nearly as light as 
raw linseed oil. There are two ordinary grades of lithographic 



MANGANATED LINSEED OIL— NITROBENZENE 221 

varnish. One is known as " burnt oil," which is obtained by 
bringing raw linseed oil up to its flash point, and allowing it to 
burn until the required thickness is reached, it being constantly- 
stirred meanwhile. "Oxygenated oil" is a linseed oil varnish 
made by treating the oil with oxygen in jacketed kettles, heated 
by steam. The product is as light colored as raw linseed oil, 
but heavier. It is also more readily soluble in alcohol, and has 
marked drying powers. 

Manganated Linseed Oil is used in certain rubber com- 
pounds where more of a drying effect is needed than is found in 
the raw linseed oil. It is linseed oil that has been boiled with 
peroxide of manganese to increase its drying qualities. See 
Boiled Oil. 

Mirbane Oil. — See Nitrobenzene. 

Mustard Oil. — Black mustard oil is obtained from the 
seeds of the Sinapis nigra. It possesses a mild taste, is of a 
brownish-yellow color, and in its chemical composition closely 
resembles rapeseed oil. It is a by-product and is largely used in 
soap making. Its specific gravity varies from 0.914 to 0.921. 
White mustard oil is made from the seeds of the Sinapis alba. 
It is yellow in color, and almost identical with black mustard 
oil. Used in making rubber substitutes. 

Neatsfoot Oil. — A pale-yellow or colorless oil, obtained 
from the feet of oxen by boiling in water. It has a smooth, 
pleasant taste. On standing it deposits stearine. It is largely 
adulterated with cheaper animal or vegetable and even mineral 
oils. Neatsfoot oil, mixed with gutta-percha, tallow, sweet oil, 
and oil of thyme, is used as a rust preventive. It is used in 
connection with beeswax, india rubber, and Burgundy pitch in 
a composition for dressing leathers or hides. Its specific grav- 
ity is 0.915 to 0.918. 

Nitrobenzene or Nitrobenzol (also called oil of mirbane 
and "imitation oil of bitter almonds") is a yellow aromatic, oily 
liquid of specific gravity 1.20, produced by the action of nitric 
acid on benzene. It is used in perfumery and turned out in 
great quantities for the manufacture of anilines. It is used also 
in certain insulating compounds in connection with asbestos, 



222 OILS IN RUBBER COMPOUNDS 

powdered glass, vulcanized rubber, castor oil, resin oil, and 
celluloid in solution. 

Oleargum. — A black viscid liquid leather dressing of an 
oily nature used as a dull finish wash for rubber boots. Its 
composition is a trade secret. 

Olive Oil is expressed from the fruit of the olive tree, 
principally in the countries of Europe bordering on the Mediter- 
ranean. Its specific gravity is 0.916. It is adulterated fre- 
quently with cottonseed oil. Olive oil is used in taking impres- 
sions from type faces in the matrix in which rubber type is 
cured. Mayall suggested the mixing of olive oil with clay until 
it formed a soft putty, and then incorporating it with india rub- 
ber, the proportion being % pound of oil to 30 pounds of gum. 
The use of the oil enabled the goods to be more largely adul- 
terated; he also used olive oil in connection with devulcanized 
rubber, not as a solvent, but because he claimed that it com- 
bined with the gum and improved its quality. Olive oil is also 
used in hard rubber compounding. Rubber is sometimes heated 
up in olive oil mixed with zinc, soap, and borax for a proofing 
solution. It is also used in the manufacture of pegamoid. 

Orris Oil is prepared from orris root. It has the con- 
sistency of butter, melts at 100 degrees F., and is miscible with 
alcohol. Its odor is like that of violets. Is used in rubber as a 
deodorizer. Specific gravity 0.949. 

Palm Oil is obtained from the fruit of various species of 
palm, principally from the west coast of Africa, and is known in 
commerce under as many names as there are ports of shipment. 
It is expressed in a very rough fashion by the natives, who stir 
the palm kernels in holes in the ground until fermentation sets 
in and the oil rises to the surface. They also sometimes press 
the oil from the fresh fruits. The harder grades of palm oil are 
yielded by the former process, the latter giving the finer oils. 
Palm oil varies in consistency. Its specific gravity is 0.945 ; its 
color yellow to reddish; its odor that of violets. It yields a soap 
readily with alkalies and dissolves in ether and in alcohol of 0.848 
specific gravity. Palm oil is very rarely adulterated, unless it is 
done by the native gatherers, who sometimes add sand as a make- 



PARAFFIN WAX— PETROLATUM 223 

weight. Commercially, where sand and water together exceed 2 
per cent., an allowance is claimed from the seller. 

White palm oil is that which has been bleached by heat, 
chemicals or exposure to the air. "Lagos oil" has about the same 
consistency as butter, while "Congo oil" is as thick as tallow. 
Palm oil is used largely in the manufacture of mechanical and 
dry-heat goods, chiefly to enable dry ingredients to mix more 
easily with india rubber. It has also been used in the recovery 
of waste rubber by mixing it with the finely ground rubber and 
exposing the mass to a heat of 572 degrees F. Palm oil residuum 
is used in connection with resin oil as an insulator. Palm oil is 
also used in the production of artificial elaterite. 

Paraffin Wax is a petroleum product. It varies in spe- 
cific gravity from 0.87 to 0.91 and in melting point from 118 
to 135 degrees F. It is a waxy substance of a white color, much 
resembling spermaceti. It is not acted upon by most of the 
chemical reagents. It has many applications in the arts. In 
rubber work it serves somewhat as a lubricant to obtain a very 
smooth surface on rubber forced through dies in tubed work. 
Also in weather-proofing insulated wires and mixed with cotton- 
seed oil it is used in certain canvas proofing. 

Peppermint Oil. — A greenish-yellow colorless oil becom- 
ing reddish with age; of strong aromatic odor, and warm, cam- 
phor-like, very pungent taste; specific gravity from 0.902 to 
0.920; used in fine goods for its odor. 

Petrolatum or crude vaseline is a rubber-compounding in- 
gredient very generally used, especially in mechanical goods. It 
is one of the numerous products of petroleum or rock oil, de- 
rived by distillation. These products are classed as follows : 
Light oils, including gasoline and naphtha; illuminating oils, 
kerosene ; residuum or tar. From the latter subdivision is sepa- 
rable, by further increase of heat, heavy lubricating and paraffin 
oils, among which are petrolatum or vaseline and coke as a 
waste product. 

It is separated from the residuum of crude petroleum which 
has been subjected to the vacuum process of distillation in con- 
tradistinction to the "cracking" process by which some of the 
natural constituents are chemically broken up to form new 



224 OILS IN RUBBER COMPOUNDS 

bodies. The residuum being kept fluid by steam, the finely 
divided coke resulting from the distillation, is allowed to settle 
out and the clear oil drawn off and filtered through fuller's earth 
contained in cylinders, in order to remove the color and odors 
contained in it. Sometimes the oil recovered from the residuum 
is treated with sulphuric acid and potassium bichromate for the 
removal of certain impurities before the filtration. This is said 
to be the German process. 

Petrolatum gains much of its value from its indifference to 
all chemical treatment. It is generally familiar as a dense prod- 
uct, dark greenish, translucent, slightly fluorescent, semi-solid, 
melting at about 100 degrees F., and having a specific gravity of 
0.850. Its chemically inert quality peculiarly adapts petrolatum 
to use in rubber compounding where a non-oxidizing lubricant 
and softener is needed to facilitate manipulation of harsh or dry 
compounds, and not subsequently develop in the finished goods 
injurious or other undesirable qualities. Any oil will soften 
rubber, but for all around adaptability petrolatum excels all 
others. 

Ordinarily 2 or 2 J / 2 per cent, of petrolatum is sufficient in 
any compound where its presence is needed, although 5 or even 
7 per cent, may be employed in special cases. Cheap goods con- 
taining petrolatum will withstand drying out or hardening with 
age, a similar effect being produced by the use of soft coal tar. 
As regards the item of economy, petrolatum commends itself 
to the rubber manufacturer when considering the use of an oil 
ingredient in compounding. For all ordinary purposes, every- 
thing except perhaps the whitest goods, the dark filtered stock 
is entirely suitable and the price will be less than the light filtered 
stock. 

Petroleum Jelly. — See Vaseline. 

Petroleum Oil (also known as Rock Oil) is a dark, ill- 
smelling liquid, obtained from wells sunk in oil-bearing sands. 
Some Russian oils, however, are colorless. White Rangoon oil 
contains so much paraffin as to have the consistency of butter. 
The specific gravity of American petroleum varies from 0.8 to 
0.85 or 0.9. 



POPPYSEED OIL—SHALE OIL 225 

Poppyseed Oil is obtained by pressing the seeds of the 
common poppy (Papaver somniferum) . Commercially there are 
two grades, white and red. This oil has no odor; it is rarely 
adulterated with other oils, although occasionally sesame oil is 
found in it; it is an excellent drying oil, and its lower grades 
are used in the manufacture of soaps; its use in the rubber in- 
dustry is chiefly in the manufacture of substitutes. Its specific 
gravity varies from 0.913 to 0.924. 

Rapeseed Oil or Colza Oil is pale yellow in color, with 
an unpleasant, hard taste. Its specific gravity is about 0.916. 
It is largely adulterated with vegetable, mineral, or fish oils. It is 
obtained from the seeds of the Brassica campestris, and of sev- 
eral varieties of this genus which are cultivated. American oils 
from all of these are termed colza or rape oil indiscriminately. 
In Europe, however, rape is one kind of oil and colza is another. 
There are also what are called the summer oil and the winter 
oil, a distinction which is of no interest to rubber manufac- 
turers. Rape oil is about half way between a semi-drying oil 
and a non-drying oil. It is used in the manufacture of rubber 
substitutes. Mixed with india rubber it has been used as a 
somewhat costly mixture for lubricating machinery. 

Rosemary Oil. — An essential oil of the specific gravity 
0.896. Colorless and having the odor of rosemary. Used with 
india rubber, paraffin, and spermaceti in waterproofing com- 
pounds, and, where rubber is present, to neutralize its odor. 

Rosin Oil. — Made by subjecting rosin to destructive distil- 
lation. Specific gravity 0.96-1.10. The resultant oil is heavier 
than mineral oils, and its chemical composition is quite involved. 
It is largely made up of hydrocarbons, with a certain amount of 
resin acids. Used in making a waterproof solution, by the addi- 
tion of Japan wax and gum thus, in the manufacture of a solu- 
tion for treating hides and leather. Used also in compounds for 
calking ships in which india rubber has a part, and is an impor- 
tant ingredient in the manufacture of guttaline. See Rosin. 

Russian Mineral Oil. — Petroleum from the Baku oil wells. 

Shale Oil. — Chiefly produced in Scotland from a dark, 
coal-like shale. It is similar in nearly all respects to petroleum 
oil. Used with asphaltum in certain insulating compounds. 



226 OILS IN RUBBER COMPOUNDS 

Stearine. — An important ingredient in animal and vege- 
table fats. It is quite solid, and increases the hardness and 
raises the melting point of fat. Commercially, stearine is also 
known as stearic acid and consolidated oil. It is an important 
element in the manufacture of cravenettes, where it is used with 
ozocerite, beeswax, paraffin, and Japan wax. Specific gravity 
0.987. 

Tallow. — Beef tallow, when fresh, is almost white, free 
from disagreeable odor, and almost tasteless. On the other hand, 
foreign tallow runs from white to yellow and is often quite ran- 
cid. Tallow is often adulterated with rosin oil, coconut oil, cot- 
tonseed oil, and paraffin wax. It is used in non-drying cements 
in connection with slaked lime and india rubber. In connection 
with india rubber it is also used in the production of what was 
known as Derry's waterproof harness oil, which was made of 
india rubber, tallow, seal oil, and ivory black. An etching var- 
nish is made of gutta-percha, turpentine, beeswax and tallow. 
A small amount of this was used by Hancock in compounding 
for softening gutta-percha. It is used with gutta-percha in shoe- 
makers' wax, and also in certain proofing compounds with india 
rubber, pitch and linseed oil. A mixture of india rubber, bees- 
wax, linseed oil and tallow makes an excellent dressing for 
leather. 

Tar Oil. — An oil distilled from tar. It is a mixture of 
several lighter oils, and is made up of liquid hydrocarbons which 
hold in solution small quantities of anthracine, naphthalene and 
paraffin. It has been recommended as a coating for rubber, it 
being claimed that it has a preservative effect. It is also used 
in compounds for surface clothing. 

Thyme Oil (also called origanum oil) is extracted from 
the flowers and leaves of the Thymus vulgaris. It is yellowish- 
red in color; its specific gravity is 0.92; and it has a pungent 
taste. It is used to disguise the odor of ale cements. 

Turpentine. — See Spirits of Turpentine. 

Vaseline is the purified residue from the distillation of 
petroleum. Its specific gravity is .875 to .945. It is insoluble in 
water, barely soluble in cold, but soluble in boiling absolute alco- 
hol, and in ether, bisulphide of carbon, oil of turpentine, benzine, 



WORMWOOD OIL - 227 

and benzol. It is the basis of a cheap waterproofing process, the 
other ingredients being silicate of soda, alum and hot water. 
Vaseline is used quite often in general compounding for its 
softening effects. It is also combined with menthol and gum 
olibanum in the manufacture of porous plasters. Vaseline has 
been used in the manufacture of substitutes similar to Rubberite. 
See Petrolatum. 

Vulcanized Oil. — These are solid dry sulphurized vege- 
table oils, commonly known as rubber substitutes. 

Walnut Oil. — Cold drawn oil is very fluid, almost color- 
less, and of an agreeable nutty flavor. Its specific gravity is 
0.926. Hot pressed oil has a greenish tint and an acrid taste and 
smell. Is used in rubber substitutes, particularly in those in 
which peroxide of lead appears as a dryer. 

White Drying Oil. — Bleached linseed oil. 

Wormwood Oil. — A pungent essential oil distilled from the 
Artemisia absinthium- employed at an early day to deodorize 
spirits of turpentine when used in rubber. 



CHAPTER XIII. 

SOLVENTS USED IN COMMERCIAL AND 
PROOFING CEMENTS. 

The beginnings of the manufacture of india rubber con- 
sisted in operations with the gum in solution and it was a con- 
siderable time before the discovery of the present processes of 
dry mixing, which are employed in the production of the greater 
part of the rubber goods now made. There are certain lines, 
however, where the use of solvents is still both necessary and 
economical. In the mackintosh manufacture, for example, the 
rubber is in almost every instance spread in the form of solu- 
tion, as a thinner coat can be spread in this way, offsetting the 
cost of the solvent. Many sheetings in various colors that only 
a few years ago were calendered, are now coated by the means 
of solution. In the making up of almost all lines of rubber 
goods, cements are necessary, and these are ordinarily made in 
the factory that produces the goods. The cements that are sold 
in bulk, such as channeling cements, for leather shoe manufac- 
turing, as well as cements that are sold in smaller packages to 
repair men in the cycle industry, all consist of rubber and analo- 
gous gum treated with some suitable solvent. Rubber being a 
hydrocarbon is soluble in the usual hydrocarbon solvents. These 
are usually those not soluble in water and of an oily nature. 

The following tables show the solubility of rubber. The 
first, which is taken from the "Journal of the Society of Chemi- 
cal Industry," is a table of the solubility of masticated caout- 
chouc. 

Ceara Para Sierra Leone 

100 Parts of: Rubber Negroheads Rubber 

Ethyl ether 2.6 3.6 4.6 

Turpentine 4.5 5.0 4.6 

Chloroform 3.0 3.7 3.0 

Benzine 4.4 5.0 { 4 " 7 

Carbon bisulphide 0.4 None. None. 

Hoffer gives, as a result of his individual experiments, the 
following table of solubilities of well-dried india rubber: 

228 



SOLUBILITY OF RUBBER RESINS 229 

Percentage 
Solvents Dry Rubber 

Bisulphide of carbon 65 to 70' 

Benzol 48 to 52 

Oil of turpentine 50 to 52 

Caoutchine 53 to 55 

Ether 60 to 68 

Camphene 53 to 58 

The great differences in solubility between various grades of 
rubber have been found to be due largely to the amounts of resins 
that are contained in them. As these resins are soluble, and in 
some cases can be removed, it is important that rubber manu- 
facturers not only appreciate their presence, but, where it is 
practicable, dissolve them out. These resins consist of abietic 
acid or similar body, according to Lascelles-Scott, who has tabu- 
lated their solubilities as follows : 

SOLUBILITY OF RUBBER RESINS. 

Normal Resin Normal Resin 

Description of (soluble in Description of (soluble in 

Rubber 85 p. c. Alcohol) Rubber 85 p. c. Alcohol) 

Para 91 Ceara 1.16 

Para 60 Assam 6.45 

Para 1.62 Assam 4.88 

Para 1.14 Burma 5.20 

Para 85 Rio 3.37 

Madagascar 4.06 Africa (various) 8.23 

Madagascar 5.22 Africa (various) 10.60 

Madagascar 2.84 Africa (various) 6.71 

Colombia 3.40 Mangabeira 8.43 

Colombia 2.11 Origin unknown 11.14 

Ceara 2.33 Origin unknown 7.27 

Ceara 1.80 Origin unknown 16.56 

In some of them oxygen is a component part, and they are 
all soluble in alcohol of 85 per cent, strength and upwards. It 
will be noticed from this table that Para rubber has the least per- 
centage of resin, and, of course, is the most valuable. The 
samples containing the largest proportions of resin were unmis- 
takably adulterated with other gums during collection. 

C. O. Weber gives the percentage of resin in a- number of 
samples of rubber as follows: 

Per Cent. Per Cent. 

Grade of Rubber Resin Grade of Rubber Resin 

Para (fine) 1.3 Sierra Leone 9.7 

Ceara 2.1 Assam 11.3 

Colombian 3.8 Mangabeira 13.1 

Mozambique 3.2 African ball No. 1 22.8 

Rio Janeiro 5.2 African ball No. 2 26.1 

Madagascar 8.2 African flake 63.9 



230 SOLVENTS OF RUBBER 

Clayton Beadle and Henry P. Stevens in their investigation 
on the insoluble constituents of Ceara and Rambong rubbers 
found that the "insoluble" and "soluble" constituents are sepa- 
rated by allowing the rubber to swell in a large excess of benzene, 
when on long standing the heavier insoluble portion collects in 
the lower half of the solution, the rubber being recovered from 
the upper and lower halves, respectively, by spontaneous evapora- 
tion. The authors concluded that their analysis and physical 
tests showed that the insoluble matter plays the part of a sulphur 
carrier and vulcanizing agent, independent of the proportion of 
the nitrogenous substance it contains. 

The patent of Frankenberg (English) covering the produc- 
tion of non-inflammable solutions of rubber is of exceeding in- 
terest as suggesting the use of new and safe solvents. Today 
few chlorohydrins are used, because of their expense, but a num- 
ber of them are on the market and the cost is steadily being 
reduced. Frankenberg's solutions are produced by mixing rub- 
ber with carbon tetrachloride, dichlor-methane, trichlor-ethane, 
tetrachlor-ethane, or trichlor-benzol, alone or together. The 
rubber may be softened with coal-tar naphtha or other solvent 
before the above solvents are added. 

RUBBER SOLVENTS. 

. Acetone is a colorless mobile liquid, with a very unpleasant 
taste and peculiar odor, and outwardly resembling alcohol. Spe- 
cific gravity 0.797. It is a good solvent for many organic sub- 
stances, and for many gums and resins. Acetone is produced by 
the destructive distillation of acetate of lime, which is one of 
the chemicals made from the products of wood distillation. It 
has a specific gravity of 0.80, boiling point of 134 degrees F. 
It is a solvent for rubber resins, dissolving about 18 per cent, of 
Pontianak resin while hot and is recommended as a solvent for 
use in analysis of rubber, as it is without action on the gum. 

Alcohol, when pure, is a colorless, thin, mobile liquid, of a 
somewhat disagreeable smell, and specific gravity 0.792. Abso- 
lute alcohol is that which has been deprived of all water. Its 
specific gravity is 0.795. It eagerly absorbs water, and, as it 
becomes more dilute, its specific gravity rises; alcohol of 60 per 



DENATURED ALCOHOL— FUSEL OIL 231 

cent, has a specific gravity of 0.883. There are a number of 
forms of alcohol used in the arts. Alcohol, chemically considered, 
embraces a large class of similar bodies. Wood alcohol or methyl 
alcohol is made from the products of wood distillation, is a 
colorless mobile fluid with specific gravity of 0.80 and a boiling 
point of 150 degrees F. and is poisonous. It is a good solvent 
for many resins, but dissolves Pontianak resin scarcely at all. 
Some of the resins of other rubbers are attacked slightly by it. 
Grain alcohol is the product of the fermentation of starch or 
sugar and in the United States is made largely from corn, rye, 
and molasses. It is chemically termed ethyl alcohol and is the 
next in series above wood alcohol. Its boiling point is 170 de- 
grees F. and its solvent powers for rubber resins is greater 
than that of wood alcohol, but some other resins are less soluble 
in the grain alcohol. It can be brought to a purity of only 96 
per cent, by ordinary distillation, and this grade is known as 
cologne spirits or neutral spirits. Dissolves readily in benzol 
but not in petroleum benzine except slightly. Dissolves fatty 
acids but not fats or fatty oils except castor oil. Soluble in most 
rubber solvents or dissolves them. Grain or ethyl alcohol is the 
most commonly used alcohol and is usually the one referred to 
unless others are specified. 

Denatured alcohol is merely grain alcohol to which have been 
added small quantities of substances which render it poisonous 
and undrinkable. The most common formula for denaturing 
alcohol is 5 per cent, wood alcohol and y 2 per cent, petroleum 
naphtha or gasoline. Many other special formulas are allowed. 
When so denatured it may be removed from the distillery with- 
out the payment of the government tax. 

Fusel oil consists of higher alcohols and is obtained in the 
manufacture of grain alcohol. It is insoluble in water and a 
solvent of many gums, and of pyroxylin or celluloid. Other sub- 
stances, for example, phenol and glycerine, are chemically alco- 
hols, but are not so called in commerce. 

None of these really are solvents of rubber, but are fre- 
quently and largely used in varnishes. India rubber solution, 
when treated with large quantities of alcohol, is deposited in a 
spongy form, the foreign ingredients in the gum going into the 



232 SOLVENTS OF RUBBER 

solution. Treated in this way it can be made an exceedingly 
white mass. It is also used in treating many of the pseudo-guttas 
to dissolve out the brittle resinous matter. It has also been 
claimed that the washing of raw rubber with alcohol dissolves 
resinous ingredients which are better absent, and that the rub- 
ber as a result lasts longer. Rectified spirit is what is generally 
used in connection with india rubber. It is used by the gatherers 
to coagulate the latex of the balata, and is used also in the pro- 
duction of resinolines (which see). One of the early uses was 
to mix with it various solvents — for instance, with spirits of 
turpentine, coal oil, bisulphide of carbon, ether, chloroform, etc. 
When ill-smelling solvents were used, it was also often incor- 
porated to neutralize the odor. Dental and other gums are 
exposed to the sunlight in alcohol to increase the brilliancy of 
the colors and to make the shades lighter. Alcohol is also used 
to soften vulcanized rubber when a surface color is to be added. 
Alcohol, in connection with nitric acid, spirits of turpentine, and 
aniline, was used by Kelly for surface work on india rubber. 

Benzol, Benzole or Benzene is a volatile oil obtained in 
the distillation of coal tar, which must not be confused with 
petroleum benzine or petroleum naphtha. Its specific gravity is 
0.899 at 32 degrees F., and 0.878 at 68 degrees F. Chemically 
it consists of 6 parts carbon and 6 parts of hydrogen. It is the 
basis for the manufacture of aniline dyes and many other coal 
tar derivatives used in the arts. It is the basis of nitrobenzene 
and aniline, the coal-tar colors. Commercially it is sold as pure, 
90 per cent, and 70 per cent. By 90 per cent, benzol it is meant 
that 90 per cent, will distil over at the temperature of boiling 
water and likewise with 70 per cent. The commercial benzol is 
to a great extent obtained from the gas produced in the distilla- 
tion of bituminous coal in the by-product coke oven. The com- 
mercial article is a mixture of benzol with higher boiling bodies 
which are very similar in their chemical properties, and these 
bodies are mostly toluol or toluene, which boils at 232 degrees 
F. and xylol or xylene, which boils at 287 degrees F. and higher 
boiling homologs. It is slightly soluble in water, and freely 
soluble in alcohol and ether, and in bisulphide of carbon. It has 
great solvent properties. Benzol is used largely as a solvent for 
rubber in manufacturing tire and inner tube cements. 



CAMPHENE— CAMPHOR 233 

Benzol is superior to carbon bisulphide as a solvent for 
chloride of sulphur and therefore is much used in the cold vul- 
canization process for curing light coated fabrics and thin, pure 
rubber goods. For this purpose benzol has the advantage of 
greater cheapness both as to price per gallon and as to lesser 
loss in handling than carbon bisulphide. This refers more par- 
ticularly to the high grades of benzol, like 100 per cent, or C. P. ; 
the 160 degrees benzol is mostly used where a solvent is required 
that must not evaporate too rapidly. It is said that if gutta- 
percha is put in 20 times its weight of boiling benzol, to which 
one-tenth of plaster is added, and the mixture agitated from 
time to time, a perfectly clear solution may be decanted. This 
is then mixed with twice its volume of 90 per cent, alcohol and 
the gutta-percha precipitated a pure white. 

Camphene is a name applied to one of the varieties of 
spirits of turpentine, which was once largely used as a burning 
fluid. It is very volatile, and the vapor makes with the air an 
explosive. Specific gravity 0.848. Camphene was formerly used 
to a certain extent as a solvent for india rubber. Under New- 
ton's method of recovering rubber, the waste was placed in a 
closed vessel, covered with camphene, and heated to 158 degrees 
F. for fourteen days. The solvent was then distilled off, and 
the tough mass remaining was capable of utilization, and was 
somewhat similar to unvulcanized rubber. It was also used in 
boot-heel cements in the old-fashioned method of attaching them 
to rubber boots, and also in general shoe cements and in varnish 
for rubber footwear. Camphene was likewise used in putting 
vulcanized waste, finely powdered, into a solution in connection 
with ether and alcohol, in a simple but somewhat expensive 
process of recovery. 

Camphor has been used as a solvent for utilizing the waste 
of vulcanized rubber and of hard rubber, the waste being first 
treated with any ordinary solvent and then placed in a still with 
a certain amount of camphor, when the india rubber is dissolved 
and the solvent passed out and distilled over again. Granulated 
camphor, over which had been passed sulphurous acid gas until 
it was reduced to a liquid, was used also as a solvent for india 
rubber, by Alexander Parkes. Specific gravity 0.990. 



234 SOLVENTS OF RUBBER 

Caoutchoucine, also spelled caoutchine, is a crude oil of 
india rubber, made by its dry distillation, and smelling much like 
naphtha. It is an excellent solvent for india rubber, but of course 
is too expensive for ordinary use. India rubber immersed in it 
swells exceedingly, and a considerable quantity of it is dissolved 
during the boiling. It must be kept in hermetically sealed ves- 
sels, as it has a great affinity for oxygen, which it absorbs ener- 
getically. In preparing it, the india rubber is treated in a retort 
at a heat exceeding 400 degrees F. Caoutchoucine dissolves in. 
ether or alcohol, and, absorbing oxygen freely, forms a resinous 
body as a result. Specific gravity 0.650. 

Carbon Bisulphide. — This excellent rubber solvent is a 
chemical prepared by the direct combination of carbon and sul- 
phur under the influence of high heat. It is a colorless liquid, 
the specific gravity of which is 1.27. Its great volatility at ordi- 
nary temperatures makes it a most rapid dryer. When mixed 
with air and heated to 150 degrees C. it will explode. Its usual 
bad odor is due to sulphureted hydrogen and the presence of 
foreign matters, from which it can be thoroughly freed by puri- 
fication. It is highly inflammable. It is a good solvent and has 
great affinity for sulphur, 100 parts dissolving 37 parts of sul- 
phur cold, or 94.5 parts at 100 degrees F. Bisulphide of carbon 
mixes with every known substance capable of vulcanizing rub- 
ber. It also assimilates rapidly with all fatty oils, and dissolves 
all the resins, with the exception of shellac. It does not dissolve 
vulcanized rubber, howeyer. Where it is used in rubber fac- 
tories care is taken, as a rule, to remove the fumes, as they are 
injurious to the workmen. Some very serious cases of chronic 
poisoning have occurred through the use of this solvent, the 
symptoms being numbness, partial paralysis, and, in some cases, 
temporary insanity. The use of bisulphide of carbon in rubber 
factories is very carefully watched, therefore, by the authorities 
in Europe, proper means for ventilation and carrying off the 
fumes being insisted upon, and minors being excluded from 
rooms where it is used. It is one of the best and most common 
solvents for india rubber, very largely used in the Parkes cold 
curing and similar processes, and in cements. 

Carbon Bisulphide Substitute, a liquid produced by Dr. 
Carl Otto Weber, is said to be a perfect substitute for bisulphide 



CARBON TETRACHLORIDE 235 

of carbon. It has these advantages : less chloride of sulphur is 
needed, the smell of the vulcanized product is sweeter, the vul- 
canizing solution penetrates deeper into the rubber, the risk of 
burning the rubber and uneven vulcanization are also done away 
with. It is also said that this substitute is not injurious to 
health. It is manufactured in England. 

Carbon Tetrachloride is a heavy, colorless, transparent 
mobile liquid, having a neutral reaction. Its odor is agreeable, 
but poisonous, resembling that of chloroform. It is non-inflam- 
mable and non-explosive. The vapors do not support combustion, 
but act as a fire extinguisher. The specific gravity of carbon 
tetrachloride is 1.6; the boiling point 77 degrees C. or 170 de- 
grees F. The liquid is insoluble in water, diluted alcohol con- 
taining less than 75 per cent, by volume of absolute alcohol and 
also in glycerine and the glycerides. It is freely soluble in ace- 
tone, glacial acetic acid, oleic acid, liquid carbonic acid and aque- 
ous solution of carbolic acid, ethyl, and amylic alcohol, chloro- 
form, carbon disulphide, benzol, ether and aniline, oil of turpen- 
tine, petroleum and all petroleum products, also in fixed and 
volatile oils and oleoresins. 

It dissolves oils, fats, resins, wax, india rubber, gutta- 
percha, cerasin, spermaceti, paraffin, stearine, varnish, asphaltum, 
pitch, balsams, coal tar, pine tar, and soda and potash soaps. 
It also dissolves salicylic acid, carbolic acid, iodine, bromine, 
iodoform, bromoform, menthol, thymol, camphor, camphor mono- 
bromate, naphthalene, etc. It also dissolves several gases, among 
others ammonia and hydrogen sulphide. It is not acted upon 
by the strong mineral acids and is not decomposed by an aque- 
ous solution of potassium hydroxide, which will, however, re- 
move any carbon disulphide or hydrogen sulphide present. 

It is strongly recommended as an extracting medium. It is 
important to remember that in contrast with benzine, gasoline, 
etc., carbon tetrachloride (C Cl 4 ) is a simple chemical compound, 
and in its recovery from the extracted fats, grease, etc., it is 
always obtained as the same chemical combination, with constant 
properties ; whereas in benzine or gasoline there are unavoidable 
losses to be sustained, particularly the valuable, very volatile 
parts, so that with a continued use of benzine the remaining less 



236 SOLVENTS OF RUBBER 

valuable ingredients, the heavier oils, must finally be enriched 
by important additions of fresh benzine or gasoline. 

An apparatus installed for the recovery of the solvents 
does not need to be remodeled for the recovery of carbon tetra- 
chloride, and the distillation process may be likewise carried 
through in the customary manner. Carbon tetrachloride does 
not in the least affect the colors of fabrics. The most delicate 
colors, even aniline colors of silk, satin, laces, etc., are not af- 
fected in the slightest degree. A mixture consisting of equal 
parts of turpentine and carbon tetrachloride cannot be ignited 
at ordinary temperatures. A mixture of 60 per cent, carbon 
tetrachloride and 40 per cent, naphtha is likewise non-inflam- 
mable at ordinary temperatures. 

Chloroform is prepared generally by distilling together a 
mixture of grain alcohol with bleaching powder and water. Its 
specific gravity is from 1.496 to 1.498. It is one of the best 
rubber solvents known. It is costly, however, and it should be 
remembered that a small percentage of chloroform in the air, 
even as little as 5 per cent., is dangerous to the workmen. 
Lascelles- Scott mentions what he calls the A. C. E. mixture, 
composed of alcohol 15 parts, chloroform 38 parts, and ether 
47 parts, which yields a powerful solvent for india rubber or 
gutta-percha. Chloroform dissolves not only india rubber, but 
fats, resins, sulphur, alkaloids, and many other organic com- 
pounds. Chloroform is used as the solvent for india rubber 
which is treated with the ammonia gas process for bleaching. It 
is also used alone, and in connection with naphtha for rubber 
cements, which are intended to adhere to glass. In the bleach- 
ing of gutta-percha, it is also used as a solvent. One of the 
first uses of chloroform in connection with india rubber is to 
be noted under an American patent granted to Charles F. Durant. 

Chute's Rubber Resin Solvent. — This is a mixture of 
methyl acetate with either acetone or methyl acetone. Patented 
in the United States in 1907. 

Dichlor-ethylene is a non-inflammable, non-poisonous sol- 
vent, of German origin. Its specific gravity is 1.269, with a 
boiling point of 181 degrees F. 

Dippel's Oil or Bone Naphtha. — A thick, viscid oil of 



ETHER— I SOP RENE 237 

brown color and very disagreeable odor, of specific gravity 0.970. 
On distillation it may be obtained limpid and colorless. It is 
prepared by the destructive distillation of bones, leaving bone- 
black as a residuum. It is chiefly used to make lampblack. It 
was one of the early solvents used for india rubber. 

Ether. — This was one of the early solvents used in connec- 
tion with india rubber. It is sometimes erroneously called sul- 
phuric ether. It is prepared usually by distilling a mixture of 
alcohol and sulphuric acid, washing the distillate, and rectifying 
the product with quicklime. It is a colorless, very mobile liquid, 
with a not unpleasant smell and is very volatile. Its specific 
gravity is 0.7183. It is soluble in water 1 to 12. Commercial 
ether boils at 96 degrees F., and yields a dense vapor. It is very 
inflammable, and when mixed with air or oxygen, gives rise to 
a dangerous explosive mixture. It is one of the best solvents 
known for oils and fats, and is also an excellent solvent for 
sulphur. For use in rubber work ether should be free from 
v/ater, but not absolutely pure, necessarily. It is little used 
today in rubber mills, except in some lines of very fine work. 
It has the advantage of being absolutely free from the objec- 
tionable odors that many solvents have. A little is sometimes 
added to naphtha to make a complete solution of india rubber. 
There are also certain processes, expensive ones to be sure, for 
treating perished rubber with ether vapor to recover it. Ether 
was used to remove sulphur from vulcanized india rubber waste 
in Newton's camphene process. 

Ethyline Chloride or "Dutch Liquid" has a specific 
gravity of 1.25. 

Gasoline. — See Naphtha. 

Heptane. — One of the four isomeric hydrocarbons of the 
paraffin series, which occurs as a colorless liquid and is derived 
from heavy cannel coal oil, petroleum, etc. Its specific gravity 
is 0.712. It is soluble in alcohol and in ether, and is used with 
paraffin wax and india rubber in water-repellent compounds. 

Isoprene. — A body found in oil of caoutchouc. It boils at 
98.6 degrees F., and possesses the property of absorbing quan- 
tities of oxygen when exposed to the air, in consequence of 
which it forms an elastic, spongy mass. Specific gravity 0.682. 



238 SOLVENTS OF RUBBER 

Isoprene is obtained by the action of moderate heat on oil of 
turpentine and is interesting as a basis for obtaining synthetic 
caoutchouc by polymerization. 

The presence of isoprene formed in a reaction of a diole- 
fine with conjugated linkings is detected by Ivan Ostromyslensky 
by shaking 5 to 10 drops of the products of the reaction for a 
short time with 50 cc. of concentrated aqueous sulphur dioxide 
solution, the mixture being then left at the ordinary tempera- 
ture in a hermetically sealed vessel. In the course of 2 to 30 
hours an abundant, colorless, amorphous precipitate is formed. 
This consists of a compound of the diolefine with sulphur diox- 
ide possessing characteristic properties. 

Isoprene may be determined quantitatively by converting it 
into 1.3-dichloroisopentane. If a grams of the dichloroisopen- 
tane compound be obtained from S grams of the crude isoprene, 
the latter contains 3403 a X 70.49 S per cent, isoprene. The 
procedure is as follows : 200 grams of the crude isoprene, con- 
taining butylenes, amylenes, benzene, etc., with boiling point 86 
to 104 degrees F., is energetically shaken with 1500 cc. of fuming 
hydrochloric acid for 6 hours in a mechanical shaker. The 
black, opaque upper layer of chloro-compounds is separated, 
washed with aqueous sodium chloride solution saturated in the 
cold, again separated after the emulsion formed has separated 
into two layers, dried over calcium chloride and distilled. At 
104 to 122 degrees F. only two or three drops of hydrocarbons 
generally distil over, and the fraction 122 to 194 degrees F. con- 
tains butylene and amylene chlorides. The fraction 194 to 266 
degrees F. is collected separately. From 266 degrees F. the 
temperature usually jumps immediately to 288 degrees F., the 
boiling point of the 1.3-dichloroisopentane. When the crude 
isoprene has been obtained, for example, from turpentine, the 
1.3-dichloroisopentane cannot be distilled, but it is found that 
the residue distilling with boiling point beyond 291 degrees F. 
consists, in spite of its black color, of almost chemically pure 1.3- 
dichloroisopentane. This residue may be filtered through glass 
wool and the filtrate weighed. The fraction boiling at 194 to 
266 F. is subjected to careful fractional distillation, as it con- 
tains 1.3-dichloroisopentane, sometimes in considerable quantity. 



METHANE— NAPHTHA 239 

The fractionation is carried out three times in each case up to 
288 degrees F. 

Methane. — Professor Lascelles-Scott describes the manu- 
facture of what he calls methane solvents, which are really ben- 
zenes or benzols through which marsh gas has been passed. He 
claims that a benzene containing from 2 to 3 per cent, of methane, 
obtained in this way, yields a better and more mobile solution 
than the ordinary solvent naphtha, and the solution when spread 
dries off better, besides giving a more finished surface. 

Naphthalene. — Commercially obtained from coal-tar, being 
among the third and fourth products of the distillation of that 
body. Naphthalene is often sold in balls made by melting the 
large silvery plates or scales in which it crystallizes, and running 
the melted compound into molds. Its specific gravity is 1.15. It 
is insoluble in water and petroleum naphtha, but the liquids de- 
rived from coal tar dissolve it easily. Naphthalene is sparingly 
soluble in alcohol and ether, but readily in benzol. It is used 
in insulating paints, as when it evaporates it leaves a very solid 
film that is said to be absolutely free from porosity. 

Naphtha. — The term naphtha was originally applied to a 
variety of pungent, volatile, inflammable liquids that belonged 
chiefly to a class of ethers ; then it took in oils of natural origin, 
such as rock oil, petroleum oil, etc. ; at a later date, a light oil 
of coal tar, which should properly be designated benzol, was 
included under the name of naphtha, while recently it has been 
extended so that it covers most of the inflammable liquids dis- 
tilled dry from organic substances. It is applied in the United 
States to a series of hydrocarbons that are obtained from petro- 
leum, whose boiling points vary with the densities, from 65 to 
300 degrees F. The naphthas of commerce are bog-head naph- 
tha, obtained from bog-head coal; bone naphtha, or Dippel's 
animal oil; coal naphtha, obtained from the distillation of coal 
tar; wood naphtha, or methyl alcohol, obtained during the dry 
distillation of wood. Of these, coal-tar naphtha and petroleum 
naphtha are most useful to rubber manufacturers. The former 
of these was used largely as a rubber solvent, but today it is 
almost wholly replaced by petroleum naphtha. 



240 SOLVENTS OF RUBBER 

Petroleum naphtha is a general name embracing a series of 
light distillates from crude petroleum. In the order of their 
lightness of gravity and boiling points the petroleum naphthas 
are: rhigolene (specific gravity about 0.665), gasoline (specific 
gravity 0.665), benzine (specific gravity 0.680-0.700), and ligroin. 

The distinction should be noted between the petroleum dis- 
tillate "benzine" and the coal-tar distillate "benzene" or benzol. 

Ligroin is a naphtha similar to benzine, used as a burning 
fluid in the ligroin or "Wonder" lamp. 

These products evaporate rapidly in a current of warm air 
and form explosive mixtures with the air. 

Coal-tar naphtha was one of the first solvents used in rub- 
ber work. Macintosh, as far back as 1823, prepared it himself 
for dissolving india rubber for proofing. There is obtained 
from crude coal-tar naphtha what is known as "once-run" naph- 
tha and " last runnings." The once-run naphtha is the starting 
point from which are derived the various grades of benzols, 
solvent naphthas, etc., by fractional distillation. The specific 
gravity of solvent naphtha should not exceed 0.875. Its compo- 
sition is very complex, including xylols, cumols, homologs of 
benzol, together with some paraffin, and sometimes a little naph- 
thalene. This last-named substance is often objectionable, as it 
acts upon some rubbers like animal oil. Naphtha derives its 
vegetable solvent power largely from the xylol present in it. 
This is today removed and sold by itself as a solvent, though the 
residual naphtha is proportionately reduced in value. 

Lascelles-Scott, after exhaustive experiments, thus describes 
three naphthas used in England in rubber factories. Petroleum 
naphtha in its solvent action on rubber showed slight action in 
the cold or under gentle heat. Viscid masses and semi-solutions 
were formed, but these solutions did not dry well. The same 
naphtha had almost no solvent action on pitch. Shale naphtha 
was useful only in dissolving Madagascar rubbers, and had no 
action on pitch, while coal-tar naphtha caused almost any rubber 
to swell quickly and, after gentle heat, effected a good solution. 
It also readily dissolved pitch, forming a deep-brown solution. 
The problem that confronts rubber manufacturers as a 
rule is the solution of gums that are more or less heavily com- 



PETROLEUM SOLVENTS 241 

pounded, which is an easier problem than the solution of crude 
rubber that perhaps has not been broken down in any way. At 
the same time it is customary in many cases to apply a little heat 
during the mixing. The following table relates to petroleum 
naphthas. The C naphtha has not only the greatest solvent 
power, but it is easier to evaporate after it has dissolved the 
rubber compound. B and A require a certain amount of heat 
to vaporize them: 

Specific Degrees Boiling 

Products - Gravity. Baume. Points. 

Rhigolene 0.625 . . 65 degrees F. 

Gasoline 0.665 85 120 degrees F. 

C. Naphtha 0.706 70 180 degrees F. 

B. Naphtha 0.724 67 220 degrees F. 

A. Naphtha 0.742 65 300 degrees F. 

Naphtha is more largely used in the proofing business than 
any other solvent. It is a general solvent for cements, and quan- 
tities of it are used in almost all lines of rubber work where 
there is any making up of separate pieces after calendering. It 
is therefore necessary that a good grade be used in considera- 
tion of the danger that may come from fires caused by the ex- 
plosion or easy ignition of low-grade solvents. Odorless naph- 
thas are those from which naphthalene, a solid white body, has 
been removed, as it is the presence of this body that causes the 
strong smell. Naphtha treated by sulphuric acid acquires a 
rather pleasant odor as a consequence. It is often mixed with 
other solvents — for example, with oil of turpentine — and is 
found thus to have a better solvent effect on the rubber. 

Pentane. — A hydrocarbon of the paraffin or methane series. 
A colorless, volatile liquid which occurs in petroleum. Boiling 
point 98 degrees F. Pentane is used with paraffin wax and india 
rubber in water-repellent compounds. Specific gravity 0.645. 

Petroleum Solvents. — The petroleum oils are by far the 
cheapest oils in commerce. They are solvents for rubber and 
are more extensively used for that purpose than any other class. 
In defining petroleum oils it is hard to make definite distinc- 
tions, for every oil is a mixture of many separate chemical sub- 
stances, and the names used to designate them in the trade and 
the tests used are indefinite and the products of no two manu- 
facturers agree in name or test. 



242 SOLVENTS OF RUBBER 

Petroleum oils consist in the main of hydrocarbons of 
several series, and a large number of each series is found in each 
kind as it is taken from the ground. 

The first oils obtained from Pennsylvania and West Virginia 
consisted of oils of the paraffin series exclusively, having the 
general formula C n H 2n +2. This series begins with marsh gas with 
one carbon atom and goes up to the paraffin waxes with many 
carbon atoms in each molecule, but each compound has the same 
ratio of carbon and hydrogen as pointed out above. 

When this oil is distilled there first passes off a little marsh 
gas which is dissolved in the oil, and following this is a series 
of products up to pentane, which boils at 36 degrees C, which 
are mostly lost, though products are sometimes made which will 
remain liquid only under pressure and will rapidly evaporate in 
the air. For example, there is a product known as cymogene 
which boils at the temperature of melting ice and has a specific 
gravity of 110 Be., and the next higher product is known as 
rhigolene, which boils at about 65 degrees F., or ordinary tem- 
perature, and has a specific gravity of 100 Be. Sometimes a 
product known as petroleum ether, boiling between these points, 
say about SO degrees C, is made. 

The next product obtained by distillation of Pennsylvania 
oil is petroleum ether of 85 degrees Be., or gas-machine gasoline, 
which is very scarce now. It begins to boil at about 50 degrees 
C. and contains some that boils at 120 degrees C. This is some- 
times called benzine, but must not be confused with the coal-tar 
benzene or benzol. 

Then there are a series of gasolines of different gravities and 
boiling points. It was customary to use gasoline of 76 degrees 
Be., but this product is now almost unobtainable, and that of 
66 Be., with a boiling point ranging up to 140 degrees C, is 
largely used. After these products come the kerosenes, or burn- 
ing oils, which are not volatile enough to be used for solvents 
which have to be later evaporated. 

The petroleum trade has clung to the use of the Baume hy- 
drometer as a standard for grading oils, and usually no other 
characteristic of the oil than its Be. gravity is used in the trade. 
While all the oil used was of the paraffin series, the Be. gravity 



PETROLEUM SOLVENTS 243 

was an indication of its relative volatility. This is now of no 
value when other hydrocarbons are present. 

When the oil of Pennsylvania became exhausted the oils of 
Ohio assumed great importance, and these were found to differ 
in many respects. While the oil of Pennsylvania was of a dark 
greenish-red of from 49 to 34 Be., it was quite mobile and rather 
transparent, and had no impurities, such as sulphur or other 
objectionable matter. The Ohio oils were found to contain large 
quantities of sulphur and required special treatment, and there 
were in them other hydrocarbons than the paraffins. Now these 
other hydrocarbons which correspond in boiling point with the 
paraffins have different specific gravities and are usually heavier, 
so that a gasoline or naphtha from them of a heavier gravity, 
say 70 Be., might have as low an average boiling point as one 
from Pennsylvania oil of 76 Be. As the products of the fields 
of Illinois, Texas, California, Wyoming, and Oklahoma came 
into the market in turn, it was found that these oils consisted 
largely of other series of hydrocarbons and that in many cases 
they contained an asphalt base instead of a paraffin base. Many 
also contained much sulphur and some contained little or no 
gasoline or naphtha. 

These oils from the western part of the United States con- 
tain large amounts of oils of the olefine series and some of the 
acetylene or aromatic series. The latter, while having a different 
gravity from the paraffin series when of the same boiling point, 
are as good for rubber solvents as the paraffin hydrocarbons, and 
indeed often better. 

In purchasing petroleum naphthas, therefore, at the present 
time it is not sufficient to ask for a naphtha of a certain gravity, 
but it must be examined and tested as to its boiling point first. 
If the oil begins to distil too low it is rather dangerous, as it 
will be more inflammable; that is, the vapors given off at ordi- 
nary temperatures will ignite easily and will carry a long way 
from their source and will explode if they come into contact with 
a light or flame. If there is much of a residue which distils 
only at a high temperature, the solvent will be too slow in dry- 
ing and the rubber dissolved in it may remain tacky. The naph- 
thas should also be tested for their dissolving power, as it may 
vary widely, according to the hydrocarbon series present. 



244 SOLVENTS OF RUBBER 

Rubber manufacturers have been confronted for a number 
of years with constantly rising prices for naphthas, and a con- 
stantly poorer grade has been received. This situation had no 
connection with conditions in the rubber trade, but was due to 
the enormous increase in demand for gasolines for motor 
vehicles. 

Pine Oil. — This is made by distillation from dead wood 
of the Scotch fir (Pinus sylvestris). It has an unpleasant em- 
pyreumatic odor. This is fatal to its use when it appears in the 
finished goods, but when it is removed the odor can be tolerated 
in the workrooms, with proper mechanical ventilation. Pine 
oil is also made from wood at the same time as turpentine, and 
is a less volatile compound. Both of these oils will dissolve 
rubber better than petroleum naphthas and as well as coal-tar 
products. 

Propylene Chloride. — The specific gravity is 1.165 and the 
boiling point 207 degrees F. 

Rhigolene. — See Naphtha. 

Rosin Oil. — This is obtained by subjecting rosin to dry dis- 
tillation, the specific gravity of the resultant oil ranging from 
0.96 to 0.99. It is rarely used as a solvent for rubber, in the 
ordinary meaning of the term. As a matter of fact, it is not a 
good solvent for crude rubber. For compounded rubbers, how- 
ever, it works well and is often used, particularly in connection 
with pseudo-guttas. In certain insulating experiments, where a 
thin sheet of gutta-percha covered the conductor, and the outer 
gutta-percha tube was full of rosin oil, it gave, according to 
Professor D. E. Hughes, F.R.S., a higher insulation test than 
gutta-percha alone. Professor Hughes used rosin oil quite thick 
and viscid, and added resin and a solid residuum obtained from 
the distillation of palm oil. Rosin oil in rubber compounding, 
however, softens the compound in a marked degree. 

Shale Spirit is the solvent used in the Scottish water- 
proofing establishments. It is a product of the Scottish paraffin 
oil industry. 

Tetrachloride of Carbon. — See Carbon Tetrachloride. 

Tetrachlormethene Benzene Substitute is an excel- 
lent solvent, boiling at 75 degrees C. Not easily ignited; of 
pleasant smell ; made from chlorine and carbon bisulphide. 



TOLUOL— TURPENTINE 245 

Thion. — A substitute for bisulphide of carbon, manufac- 
tured in England, said to mix excellently with chloride of sul- 
phur, and is non-poisonous. 

Toluol or Toluene. — That oil which is distilled from coal 
tar at a temperature of 230 degrees to 234 degrees F., also called 
methyl benzene and toluole. Specific gravity 0.872. It resembles 
benzene in outward appearance. Much commercial benzol con- 
tains toluene, which makes it a far better solvent for rubber than 
benzene itself, as it dissolves the rubber in five-sixths of the time. 
The solutions are more mobile; it has a higher boiling point; 
and, given a quantity of the solvent, will dissolve more gum even 
at low temperature. It leaves a more solid deposit of rubber 
than benzene, and does not induce headache or sickness. 

Turpentine (crude) is known as an oleo resin, and is of 
about the consistency of fresh honey. There are more than a 
dozen varieties on the market, the more common being Bor- 
deaux, Venice, Canadian, and American. A fair quality of tur- 
pentine oil should begin to boil at 155 degrees C. or 311 degrees 
F. The distillation of crude oil of turpentine by steam leaves 
ordinary rosin. Oil of turpentine is used in certain waterproof 
cements, in connection with both gutta-percha and india rubber. 
Where oil of turpentine is necessary for rubber work, it is well 
to have it free from the considerable percentage of water which 
it invariably contains. This is done by a treatment with sul- 
phuric acid, or by rectifying it over burnt lime. Turpentine, 
particularly that known as Venice turpentine, is often used in 
connection with linseed oil and sulphur in the production of 
rubber substitutes. Professor Tilden showed, some years ago, 
that what appeared to be pure india rubber could be obtained 
from turpentine; indeed, he announced that he had produced it 
on a small scale. The same thing was also observed by Bou- 
chardat. Venice turpentine is obtained from Switzerland, where 
it is procured from the Larix Europea, or larch. The genuine 
Venice turpentine is of the consistency of honey, cloudy, yel- 
lowish, or slightly greenish. It is entirely soluble in alcohol. 
The commercial Venice turpentine is a factious substance, usually 
quite brown, and is prepared by dissolving rosin in oil of tur- 
pentine. Venice turpentine is largely used in cements. Bor- 



246 SOLVENTS OF RUBBER 

deaux turpentine is the ordinary turpentine of commerce, get- 
ting its name from the port in France whence it is exported. 

Turpentine Oil or Spirits of Turpentine has a specific 
gravity of 0.864. It is colorless, transparent, with strong odor, 
and bitter taste. It is insoluble in water, on which it floats, 
but readily soluble in strong grain alcohol, ether, and the fixed 
and essential oils. It is an excellent solvent for sulphur, resin, 
and india rubber. Spirits of turpentine, with wood spirit alco- 
hol, aniline, and nitric acid is used in surface work on vulcan- 
ized india rubber. The earliest records of india rubber speak 
of this oil as a solvent; indeed, the whole secret of rubber com- 
pounding for a number of years, when the great Roxbury Rubber 
Co., of Boston, was running, was the solution of india rubber 
in turpentine. It is used in solutions that are expected to be 
sticky, and to dry slowly. 

Vulcoleine is a liquid of English origin, and is put upon 
the market at about the same price as carbon bisulphide, and 
used for a solvent for india rubber. It leaves on evaporation 
a perfectly tough and elastic film, quite unlike that left by coal- 
tar naphtha, or the usual solvents. It mixes instantly with 
chloride of sulphur, and is intended to replace bisulphide of 
carbon in the cold-curing process. It has no bad smell, nor is 
it unhealthful. 

Wood Spirit. — See Alcohol. 

Xylol. — A colorless, somewhat aromatic, inflammable, oily 
liquid distilled from coal tar and wood tar; also called xylene. 
It is similar to benzol and toluol. Specific gravity 0.882. 



CHAPTER XIV. 

MISCELLANEOUS PROCESSES AND COMPOUNDS 
FOR USE IN THE RUBBER FACTORY. 



SURFACE COLORING AND PRINTING. 

The formulas given below for the dyeing and surface color- 
ing of rubber, although interesting, are not such as will gener- 
ally be used. 

A suggestion for coloring that comes from France is the 
dipping of rubber for an instant in a bath of nitric acid, then 
washing in water. Next, the rubber is dipped for coloring in an 
alcoholic solution of fuchsine. The experimenter should appre- 
ciate fully, however, the effect that nitric acid produces on rub- 
ber, and govern himself accordingly. 

Alexander Parkes, who produced some exceedingly valu- 
able processes for the treatment of rubber, gives the following 
formulas for dyeing india rubber: 

Black. — Boil from 15 to 30 minutes in a liquid prepared as 
follows: sulphate copper, 1 pound; water, 1 gallon; caustic 
ammonia or muriate of ammonia, 1 pound. Or: sulphate or 
bisulphate potash, 1 pound; sulphate copper, 12 pounds; water, 
1 gallon. 

Green. — Muriate ammonia, 2 pounds; sulphate copper, 1 
pound; caustic lime, 4 pounds; water, 1 gallon. Boil the rub- 
ber as before, 15 to 30 minutes. 

Purple. — Sulphate or bisulphate of potash, 1 pound; sul- 
phate of copper, Y4. pound; sulphate of indigo, % pound. Boil 
the rubber, 15 to 30 minutes. 

Hoffer gives almost the same ingredients for producing 
these colors, adding the information that the articles are dyed 
by being boiled in these fluids from 15 to 30 minutes, the thicker 
the article the longer the boiling. This is done before the goods 
are vulcanized. 

247 



248 MISCELLANEOUS PROCESSES 

Hard rubber may be decorated by means of pigments mixed 
with shellac and applied to the given surface with a brush. The 
surface then is to be pressed with some force against a hot 
plate of metal, whereby the colors are made to appear as though 
integral with the rubber. 

Wood coated a sheet of vulcanized rubber with chloride of 
silver, the idea being to use it in dental plates. Various processes 
have also been brought out for the surface treatment of rubber 
with gold leaf, bronzes, etc., usually applied in the form of 
powders, in the manner in which flock (powdered fiber) is ap- 
plied. Truman also patented a process for electro-gilding rubber 
dental plates after they were finished. 

Goodyear dusted unvulcanized rubber surfaces with plum- 
bago or powdered metal, to make them electrically conductive, 
pressed the dust in, and then electroplated upon it. 

The embossing of india rubber surfaces has been practiced 
almost since the invention of Goodyear's " triple compound." It 
is really nothing more than a light surface molding. This is 
done sometimes by embossing rolls, the rubber being cured after 
the impression is taken, and sometimes by being vulcanized on 
the impression plate. 

Bourbridge patented a process for embossing rubber by 
rolling it tightly on a drum with embossed paper or bookbinders' 
cloth, and semi-curing it in that form, preferably by boiling in 
water at a temperature from 212 degrees to 220 degrees F. 
This boiling operation was not really vulcanization, but simply 
a means of setting the rubber, which was afterward made up 
into goods and cured. 

In producing sheets of india rubber for the manufacture 
of tobacco pouches, balls, balloons, etc., by this process, the 
sheet is calendered on sized cloth, partially vulcanized, printed, 
coated with transparent india rubber, the goods made up, and 
the vulcanizing process completed. 

Printing on inflatable thin rubber films, such as toy balloons, 
may be neatly done by applying the inflated article to the inked 
type or electrotype. 

A great many beautiful colors are added to india rubber 
surfaces by coating the sheet with a thin adhesive solution, dust- 
ing it over with colored flock, and then vulcanizing. By this 



COLORED DESIGNS FOR FABRICS 249 

process any color can be given to rubber surfaces which are to 
have a cloth-like appearance. 

Kelley produced a bronzed appearance on rubber-coated 
fabrics by means of a roller partly immersed in a trough hold- 
ing the dye, curing either by dry heat, or by chloride of sulphur. 
His solution consisted of 2 ounces alcohol spirits, 1 ounce wood 
naphtha, 10 drops nitric acid, 1 ounce spirits of turpentine (with 
sufficient aniline dye to make the desired color), 4 ounces liquid 
dyeing, 3 pounds rubber composition. He also impregnated 
farina with aniline solutions, dried it, and mixed it in the com- 
pound. 

In certain dyeing processes lakes are necessary. A caout- 
chouc lake is made by steeping 1 ounce of Para rubber in a quart 
of light camphor oil, exposed to the sunlight for several days. 
This is said to be excellent for binding colors. 

Matthew's process for producing colored designs for proofed 
fabrics is to first coat the fabric in the ordinary manner with 
pure or colored india rubber. When the design is to be printed 
on a black or dark ground, the last coating is mixed with starch 
or some powder that will render it non-adhesive, and to an ex- 
tent absorptive. The fabric is then partially vulcanized, when 
the designs are printed on the desired surface. The vulcanization 
is finished preferably by using chloride of sulphur. 

Colors suitable for admixture with rubber should answer 
the following requirements : they must be unaffected by water, 
acids, alkalies, or chloride of sulphur. Further, they must not 
be affected by sulphur at temperatures ranging from 200 degrees 
to 300 degrees F. The colors must not be soluble in or affected 
by naphtha or other solvents used in rubber work. According 
to Frankenburg, his invention of aniline lakes answers all these 
requirements. His description is as follows : 

(A.) Lakes prepared from acid aniline colors. — "I have 
found that by converting any of the acids or suphonated aniline 
colors into compound lakes, such as barium-alumina, calcium- 
alumina, barium-chromium, or calcium-chromium lakes, colors 
are obtained answering all the above requirements, and there- 
fore eminently suitable for the dyeing of india rubber, water- 
proof, and other articles. The aniline dyes best suited for the 
production of these lakes are those known as azo or di-azo col- 



250 MISCELLANEOUS PROCESSES 

ors. From colors of this description I prepare lakes in the fol- 
lowing manner : 50 pounds of orange II., or any other suitable 
azo or di-azo color, and 112 pounds of soda crystals are dis- 
solved in 100 gallons of water at 170 degrees F. This solution 
is then precipitated with a solution of 150 pounds of barium 
chloride. The precipitate is kept boiling for half an hour. It 
is then left to stand, and washed several times with fresh water. 
Eventually a solution of 40 pounds of alumina sulphate is added 
very gradually, when a bright, fast, and flocculent lake is ob- 
tained, which, after nitration, drying, and pulverizing, is ready 
for incorporation with the india rubber dough. It is evident 
that a great many variations of the process may be devised, but 
in every case the important point is the conversion of the ani- 
line dye into one of the above-mentioned compound lakes. As 
regards the proportions given above, they are, of course, sub- 
ject to such variations as are in accordance with the molecular 
weights and the commercial purity of the materials used, as well 
as with the particular properties and qualities to be imparted to 
the lakes for the purpose they are intended to serve. Using in 
this manner the numerous azo and di-azo dyes a very great 
variety of lakes may be produced, comprising all conceivable 
shades, and all suitable for the dyeing of india rubber articles of 
every description. The lakes prepared from the acid oxy-ketone 
dyes and most of the natural dyes are very suitable for this pur- 
pose owing to their indifferent and dull shades." 

(B.) Lakes prepared from basic coloring matters. — "A 
large number of lakes derived from this class of dyes are also 
suited for the dyeing of 'india rubber articles, although many of 
them are lacking in fastness to light acids and alkalies. To pro- 
duce a perfect compound lake from these dyes tannic acid and 
antimony, along with aluminum and barium, are used for the 
complete fixation and precipitation of these lakes. . The follow- 
ing proportions give good results : soda carbonate, 128 pounds ; 
barium chloride, 110 pounds; thioflavine, 25 pounds; tannic acid, 
20 pounds ; acetate of soda, 20 pounds ; sulphate of alumina, 100 
pounds. These colors can be made faster by adding to them a 
small quantity of antimony potassium-tartrate. The proportions 
of tannic acid, sodium acetate, and tartar emetic used in this 
process vary considerably with the different basic colors, such 



THE CRAVENETTE PROCESS 251 

variations being due to the difference in the atomic weights and 
commercial purity of the basic dyes." 

Hebblewaite and Holt's process for producing designs on 
gossamer cloth calls for spreading farina or other powder over 
the rubber surface, then running the fabric through embossed 
rollers and producing patterns thereon. 

Mosley's ornamented fabric was a gossamer cloth covered 
with farina, the surface being printed much as calico is, and 
then vulcanized with chloride of sulphur. The colors were mixed 
with suitable solvents and a certain amount of paraffin or india 
rubber added. A part of this invention was also the use of an 
engraved roller, which revolved in the vulcanizing solution, and 
came in contact with the surface of the rubber, only at its raised 
portion. Directly after passing over the roller, the surface of 
the rubber was dusted with farina, which adhered to the por- 
tions that had come in contact with the roller, and not to the 
rest, thus producing a design on the fabric. The whole of the 
coating was afterwards cured by vapor. 

Impregnating Rubber. — Lessnenn and Weinkopf advise 
the brush application of the following to prevent sun-cracking: 
Sixty per cent, birch tar oil ; 38 per cent, coal-tar benzene ; 2 per 
cent, dissolved dextrine. 

SHOWER-PROOF PROCESSES. 

The Cravenette and other processes for rendering textile 
fabrics waterproof or water-repellent have attracted so much 
attention in the rubber trade that space will be given here to a 
description of the Wiley patent, which is used at the Cravenette 
Works, Bradford, England. 

The waterproofing compound is applied in a solid or hard 
state by the action of friction and heating. No solvents are used, 
nor is it a calendering process. The advantage of this is a lessen- 
ing in the cost of applying waterproofing solutions and a further 
valuable result is that the dyes on various fabrics are in no way 
disturbed, and no unpleasant odor is developed or imparted to 
the cloth. The substances chosen are those which have a low 
melting point, so that the fabrics are not damaged by heat. They 
are preferably ozocerite, stearine, spermaceti, paraffin wax, bees- 
wax, or Japanese wax. These are sometimes used singly, and 



252 MISCELLANEOUS PROCESSES 

sometimes in combination, considerable judgment being neces- 
sary in selecting those which have an affinity for or are readily 
absorbed by the fibers of particular fabrics, influenced also by 
the nature and color of the fabric. In some cases india rubber, 
gutta-percha, maltha, asphaltum, resin, and artificial gums are 
found valuable in small proportions, and in conjunction with the 
substances already mentioned. 

In order to apply the waterproofing substance, it is formed 
into slabs. The fabric is carried on a reel supported in bearings 
between suitable frames, at the opposite end of which is a hol- 
low cylinder mounted upon carrying rollers and supported later- 
ally by side rollers. This cylinder is filled with water. The 
slab of the compound, wider than the fabric to be coated, is fixed 
in a holder above the cylinder. This holder is so arranged that 
the weight presses the slab against the cylinder. The fabric is 
then drawn from the reel over and under tension bars, under a 
supporting roller, between it and the rubber cylinder, and around 
the cylinder and under the slab, then over the guide roller and 
into a drying machine. The friction of the cloth wears the slab 
away and uniformly deposits it upon the cloth while in the dry- 
ing machine, the heat melts the waterproofing compound, and it 
is absorbed by the fibers, which are thereby rendered waterproof 
or water-repellent. 

Other formulas for shower-proofing and waterproofing are 
of interest in this connection and a few are given: 

A German waterproofing compound: alum, 10 pounds; 
sugar of lead, 10 pounds. Dissolve in hot water and allow the 
precipitate to settle. Dilute the clear liquid with 120 gallons 
water and add 2 pounds isinglass in solution. The goods are 
steeped in this solution 8 or 10 hours. 

An American shower-proof compound: liquid silicate of 
soda, 1 gallon; white oxide of zinc, 1 pound. If the fabric is 
to be colored, add coloring matters. The mixture may be applied 
to fabrics hot or cold, by means of a brush or by immersion of 
the fabrics, which are afterwards to be run between rollers. 

Another American compound: dissolve separately, 1% 
pounds alum (in hot water), 10 ounces acetate of lead (in hot 
water), and \]/ 2 pounds carbonate of magnesia (in hot water). 
They should aggregate about 31 quarts. Add the acetate of lead 



SHOWER-PROOF COMPOUNDS 253 

to the alum solution, and then the carbonate of magnesia; after 
which 10 quarts liquid as above and 1 tablespoonful white gum 
arabic. Stir y 2 hour; let stand 24 hours, skimming now and 
then ; in 48 hours the first mixture will be ready. Lay the fabric 
in a vessel and pour liquid over it, beating the fabric well and 
removing it within an hour. 

A third American shower-proof compound : 

A. Carbonate of soda 16 parts. 

Lime 8 parts. 

Water 32 parts. 

Boil 30 minutes, let settle and pour off the clear lye. 

B. Glue or gelatine 3 parts. 

Linseed oil 3 parts. 

Add after soaking glue in cold water 12 hours. 

C. Tallow (or other animal fat) 16 parts. 

Rosin 8 parts. 

Melt together. 

To (A) boiling hot add hot (C), then pour in (B) 
and stir hot until well mixed. 

D. Sulphate of alumina 1 pound. 

Acetate of lead y 2 pound. 

Boiling water 8 gallons. 

Let settle and draw off clear liquor for use. To 1 gallon 

water add y 2 ounce of first product for bath for cotton goods. 
Add Ya. ounce for silk or wool. Immerse 24 hours or more, then 
six hours or more in second compound (D). 

Proofing compound : 

Mixture 1. — Dissolve in water, 50 parts alum; also dissolve 
in water, 35 parts sugar of lead; mix. 

Mixture 2. — Combine 17 parts paraffin and 35 parts benzine; 
drop into this 17 parts caoutchouc. Stir until well dissolved. 

Mixture 3. — To the clear decanted liquor from the above 
mixture, add 8 parts alcohol and 4 parts eau de cologne (or oil 
of lemon). 

An English compound for waterproofing textile fabrics: 
sugar soap, 1 pound; water, 16 gallons. Soak articles in them 
for 6 hours; drain, but do not wring them; and place them in 
the following solution: alum, 1 pound; water, 16 gallons; soak 
again 6 hours, take out and dry without wringing. 

Another English compound for waterproofing textile fab- 
rics : concentrated size, 8 pounds ; aluminum sulphate, 5 pounds ; 
barium chloride, 6 pounds; water, 16 gallons. After coating, 
varnish with the following : Melt together 22 pounds colophony, 
4 3-5 pounds crystallized soda, and 11 pounds water. Then add: 



254 MISCELLANEOUS PROCESSES 

ammoniacal fluid, 5% pounds; and water, 55 pounds; or: borax, 
6 pounds ; shellac, 6 pounds ; and water, 40 pounds. 

A German compound for waterproofing woolens : dissolve 
100 pounds alum in moderate quantity of boiling water; soak 
100 pounds glue till it has taken up twice its weight of cold 
water, then apply heat to dissolve it ; stir 5 pounds tannin and 2 
pounds soluble glass well into the glue, then add the alum solu- 
tion. Enter the goods at 80 degrees C, and steep 30 minutes. 
Take out and drain several hours, stretch on a frame, and, when 
dry, calender. 

A German shower-proof compound: stir 9 pounds casein 
well in 32 quarts water, adding little by little 25 pounds of slaked 
lime. Add a solution of A J / 2 pounds soap in 26 quarts water. 

Filter and treat the cloth with the liquid. Dress with a 
dressing of acetate of alumina, by which the casein is rendered 
insoluble in the fibers of the cloth. After two applications, rinse 
the goods with hot water, press strongly, and dry. 

One process for waterproofing threads and yarns used in 
weaving ducks and other fabrics is in two parts, the first of which 
relates to a tanning mixture in which the yarns are immersed, 
consisting of: birch bark, 14 pounds; bichromate of potash, 1 
pound; chloride of calcium, y 2 pound; tar, 1 pint; solution of 
alkali, 2 pounds. The threads are first boiled in a 5 per cent, 
solution of alkali to destroy perishable matter, after which they 
are immersed in the tanning liquid and dried. The second pan 
consists of preparing or dressing the threads with the following 
compound : poppyseed oil, 2 gallons ; india rubber solution, 2 
pounds ; red oxide of mercury, 1 pound ; resin, 28 pounds ; bees- 
wax, 28 pounds; palm oil, 14 pounds. The threads after this 
treatment are wound on reels for weaving. 

Forster, in 1847, made a water-repellent compound in which 
he used spermaceti, wax, and stearine, while three years prior 
to that Townsend used two solutions to accomplish that end, 
the first being water, calcined British gum, white soap, logwood 
liquor, and alum; the second being water, sulphate of zinc, cal- 
cined British gum, and palm soap. 

The kyanized cloth process is well known in connection with 
preserving fabrics, the treatment being with a mixture of cor- 
rosive sublimate, chloride of zinc, pyrolignite of iron, oil of tar, 



WATERPROOF FABRICS 255 

and resinous matters. Fabrics treated in this way have been used 
for the manufacture of hose. 

According to Dr. Doremus the lightest fabrics are rendered 
uninflammable by dipping them in a solution of phosphate of 
alumina in water. 

Allard's fireproof felt is made of 50 per cent, of asbestos and 
50 per cent, of animal hair, and for ordinary purposes is wholly 
fireproof. 

Canvas for sails and other purposes, which it is desired to 
render waterproof, is treated by the Dumas process so that, while 
it is both waterproof and fireproof, it is still elastic and permeable 
by air. The treatment is this: The material is first put in a 
solution of gelatine, then run through pressure rollers, and spread 
in the open air to dry; later it is dipped in a cold solution of 
alum, again exposed to the air, then washed in cold water, and 
finally dried. 

Frankenburg's waterproof cloth is made in this manner: 
Both warp and woof are coated in the yarn with india rubber, 
then powdered with farina, then woven, after which the fabric 
is calendered, and the result is a cloth that is thoroughly water- 
proof, and yet does not give evidence of having rubber in its 
make-up. 

Smith's porous waterproof fabric called for a compound 
made of 100 parts of paraffin melted by heat, to which was 
added 15 per cent, of india rubber, the mixture being kept from 
5 to 30 minutes at a temperature of 100 degrees C. The solu- 
tion, either as it is, or with a solvent, is then transferred to the 
cloth by means of a set of rollers which have a temperature of 
about 70 degrees C. 

Amphiboline. — A natural earth found in Germany, which 
once mixed with water, will not mix again. Used with a small 
amount of gelatine for waterproofing. Formula: 34 parts am- 
phiboline, 9 parts gelatine, 2 parts chrome alum, 2 parts ammo- 
nium sulphate, 53 parts water. 

Cohuru's waterproofing compound: This consists of crude 
petroleum, 3 quarts; liquid asphalt, 1 pint; white drier, 1 pint; 
beeswax, 4 ounces, and gum-arabic. 



256 MISCELLANEOUS PROCESSES 

DEODORIZATION. 

The odors that cling to vulcanized rubber goods and to 
gutta-percha are often very objectionable, and the following 
processes are given for deodorization : 

Cattell's process: For every pound of well-cleaned gutta- 
percha take 15 pounds of the following solution: benzol, 1 gal- 
lon ; alcohol, 1 ounce ; glycerine, 30 drops. Or benzol, 1 gallon ; 
nitrate of the oxide of ethyl, 30 drops; heat in a closed vessel 
to 110 degrees F. The gutta-percha is recovered by cooling to 
below 32 degrees F., and pressing or by distilling off the sol- 
vent, or by precipitation with fusel oil. 

Freeley's process : dip vulcanized rubber goods in a solution 
of : salicylic acid, 20 grains ; alcohol, J / 2 pint. This will deodor- 
ize them, but goods will be toughened and the deodorization in- 
creased by subjecting goods to a bath in hot or cold solution 
composed as follows: 

(A) Oak bark, 50 pounds; hemlock bark, 50 pounds; sumac 
bark, 50 pounds; water, 900 gallons. 

(B) Solution as above, 2 gallons; salicylic acid, 20 grains; 
large tablespoonful of Russian jackten extract, dissolved in 2 
pints of alcohol, 1 pint of ether, and 10 grains of salicylic acid. 

Bourne's process: The articles to be deodorized are placed 
between layers of charcoal and heated from 120 degrees to 150 
degrees F., if unvulcanized ; 180 degrees F., if partially vulcan- 
ized; or 212 degrees F., if completely vulcanized. Heat for six 
hours or more. 

Lavater and Tranter's process: Subject the articles to a 
boiling in potash, then to a vacuum, then to a pressure of air 
scented with some essence. They claim the extraction of the sul- 
phur from the pores of the rubber in the form of sulphureted 
hydrogen and its replacement by perfumed air. 

Charles Hancock's process : To remove the odor of gutta- 
percha, steep it in the following solutions: 

(A) Soda or potash, 1 pound; water, 10 gallons. 

(B) Chloride lime, 1 pound; water, 10 gallons. 
De la Granja's process: 

Iodine 15 grains. 

Permanganate of potassa 20 grains. 

Iodide of potassium 60 grains. 

Glycerine 4 ounces. 



PRESERVATIVE PROCESSES 257 

De la Granja's process (Continued) : 

Sulphite of soda 4 ounces. 

Sulphite of lime 4 ounces. 

Sulphite of potassa 4 ounces. 

Water V/ 2 to 2 gallons. 

Soak rubber in a solution composed as above, in a close 
earthen vessel, 24 hours, the solution being cold. Then heat the 
solution gradually to boiling point and uncover the vessel until 
}i of weight of solution evaporates. When the solution cools 
remove the rubber. 

The Traun Rubber Co. patented a process for adding pow- 
dered perfumes to india rubber, the stock being used for dental 
dam, dress shields, and the like. 

PRESERVING RUBBER GOODS. 

The deterioration of vulcanized rubber goods is often a 
serious matter, where it is necessary for some time to keep them 
in store. Wherever possible, they should be kept in a cool, dark 
place, and away from warm currents of dry air, and free from 
contact with oil of any kind. Soft rubber articles are often pre- 
served by being kept submerged in water. Such articles would 
naturally be small in size and contain no exposed fabric or 
metallic parts. A typical list would be, tubing, catheters, bulbs, 
stoppers, etc. 

The cause of brittleness Ahrens looks for not in the meth- 
ods of storing but in unsuitable mixings and wrong vulcaniza- 
tion. 

Where one is forced to use chemically active fillers, sub- 
stances should be added to retard oxidation. Using petroleum, 
benzol, aniline, pyridine, etc., to regain the elasticity of hard- 
ened rubber has, in the end, the opposite effect. The softening 
lasts only as long as the solvent is present; after its disappear- 
ance there is hardening again and an acceleration of the degene- 
rating process, 

It has been advised that such goods as druggists' sundries 
be stored in an air-tight receptacle in the bottom of which is 
placed a vessel containing benzine, which is allowed to evaporate 
slowly. Kreusler and Bude in Der Techniker recommend the 
dipping of the articles in a paraffin bath, heated to about 212 
degrees F. This does not injure the color or the appearance, 
but is said to enable the goods effectually to resist both light and 



258 MISCELLANEOUS PROCESSES 

atmospheric influences. From its well-known softening effect 
on india rubber, however, paraffin is likely to be used with con- 
siderable care by rubber manufacturers. In the line of mechani- 
cal goods, Turner patented a process for treating both hose and 
tubing with carbolic acid, either during its manufacture or after 
vulcanization, in order to preserve it. Torrey also saturated duck 
with carbolic acid before it was made up into hose. 

Mowbray's process for preserving rubber in valves : The 
use of 20 pounds of india rubber, washed and cut fine, in con- 
nection with 5 to 10 pounds of naphthalene; digest 24 to 48 
hours, at 180 degrees to 230 degrees F. Masticate in a machine 
heated to 212 degrees F., until it forms a plastic homogeneous 
compound. If other substances are to be added, treat as follows : 

1. Soluble matters (sulphur, antimony, resins, etc.) dissolve 
in naphthalene, melted or boiling, -and add to above naphthalized 
caoutchouc at temperature of 240 degrees F. 

2. Materials insoluble in naphthalene (oxides of lead and 
zinc, chalk, etc.) deprive of moisture and heat to 212 degrees F. 
and add to naphthalized caoutchouc. 

This compound can be used for soft or hard rubber, accord- 
ing to the proportion of sulphur used. The object is to preserve 
the elasticity of rubber and prolong its durability. 

Trueman's process for preserving india rubber, and fibers 
that may be used with it, employs the peroxides of manganese 
and lead and the black oxide of copper, all of which have the 
property of decomposing ozone in great quantity, and convert- 
ing it into oxygen. The inventor believes that ozone is the active 
agent in producing decay, and, by changing it into oxygen, he 
arrests such decay. In applying these oxides, he mixes them 
with ozocerite or tar. 

Elworthy patented a process for storing rubber goods in a 
receptacle filled with nitrogen, hydrogen, marsh gas, or carbonic 
acid gas. This was recommended especially for rubber goods in 
India. 

Benton (American patent) describes the following: A com- 
position for preserving india rubber, consisting of one part tur- 
pentine, as much camphor gum as the turpentine will readily dis- 
solve, and one part linseed oil proportioned to the combined part 
of turpentine and camphor gum. 



UNITING RUBBER TO METALS 259 

Truss (English patent) advises : A mixture of 95 parts of 
soda-ash and 5 parts of commercial carbonate of ammonia is 
dissolved in hot water and applied to india rubber articles to 
preserve or restore them. 

Zingler's process treats decayed rubber goods by long solu- 
tion in boiling water containing tartar emetic; mixed afterwards 
with tannic acid and calcium sulphite. 

UNITING RUBBER TO METALS. 

The problem often comes to rubber manufacturers to vul- 
canize rubber or rubber compounds to iron so that they will not 
part from it under strain. This is done successfully by a num- 
ber of different formulas. Where the processes are skilfully 
carried out, the rubber should adhere so firmly to the iron that 
it will give way anywhere else in the mass, except where its sur- 
face is in contact with metal. The usual chemical basis of these 
processes is the affinity of the sulphur in the rubber mixing for 
copper deposited on the metal. 

For ordinary roll covering the cast-iron roll is rough turned, 
after which all grease is removed from the surface by washing 
with naphtha and exposing the roll to open steam for an hour in 
the vulcanizer. The thoroughly dry, clean roll is then cemented 
with a hard-curing rubber cement, upon which is applied a layer 
of hard-rubber composition, followed by a layer of compound 
curing intermediate in hardness, and this, in turn, by the softer 
curing main body of rubber. 

Attachment by Melting. — The effectual attachment of 
rubber to iron, applicable in the case of hand-power clothes^ 
wringer rolls, is by the process of cementing by melting. In 
detail it is accomplished as follows : The metal shaft is brought 
to dull redness its entire length and is then used to melt or burn 
out the hole in the previously vulcanized roll, enough to thor- 
oughly smear both hole and iron their entire length with sticky 
compound. The iron is then quickly quenched in water to a heat 
below the melting point of the rubber. At this stage the roll is 
replaced on the shaft and, with a few blows on the shaft on the 
anvil, jarred down in place. The heat remaining in the shaft is 
sufficient to cure the roll so firmly to the iron that on cooling 
it can only be removed by cutting away the rubber. A little 



260 MISCELLANEOUS PROCESSES 

practice is necessary to judge properly the heat of the iron after 
quenching, that it may not continue melting the interior of the 
roll and produce a cavity or unattached spot. 

Solid Tires to Steel Rims. — The steel rims for solid 
motor-truck tires are provided with coarse grooves to add in- 
creased surface and protection against side slip of the hard-rub- 
ber ply uniting rim and soft rubber. Frequently the rims are 
electroplated with brass for chemical union with the hard rubber 
and sometimes the grooves are undercut or dove-tailed in form 
to add an interlocking grip. The rims are brushed and cleaned 
with naphtha, cemented with hard-rubber cement and, when 
thoroughly dried, the hard-rubber ply is forced into contact with 
the cemented surface with complete exclusion of the air between. 
The hard- rubber surface is rendered adhesive with cement and 
the soft-rubber body of the tire applied. Vulcanization in a 
mold under extremely heavy pressure in a vulcanizer-press ren- 
ders the attachment of steel and rubber permanent. 

The Garrity and Avery patented process is as follows : ni- 
tric acid (41 degrees Baume), 10 gallons; muriatic acid (22 
degrees Baume), 10 gallons; mix and add pure tin, finely 
divided, 10 pounds. Immerse the iron for 8 seconds, remove and 
dip into weak solution sulphuric acid, then wipe with a woolen 
cloth. Then apply with brush, or otherwise, the following com- 
pound : rubber cement, 7j/2 gallons ; litharge, 6 pounds ; and sul- 
phur, 3 pounds. Apply vulcanizable rubber compound at once, 
and vulcanize. 

Hall's process : Water, 100 quarts ; caustic potash, 10 pounds ; 
cyanide of potash, 2 pounds ; sulphate of copper, 2 pounds ; sul- 
phate of zinc, 2 pounds. The pickle and bath are made of water 
and about 10 per cent, sulphuric acid, the tub being lined with 
brass plate. 

Adam's process : A weak solution of sulphate of copper is 
made — say 2 or 3 ounces of the crystallized salt to the gallon — 
and this solution may be acidulated with sulphuric acid — say 
ibout l / 2 gill of strong acid to the gallon. For a fine film for 
"dipping" articles of iron, steel, or tin, to which the rubber com- 
pound is to be applied, if the metal is copper, it should first be 
coated with tin, nickel, or iron. 



GAS PROOFING 261 

The shellac process calls for a cement made of shellac steeped 
in ten times its weight of concentrated ammonia, the solution 
being allowed to stand three or four weeks. This solution is 
painted on the iron, allowed to dry, and the rubber vulcanized 
upon it. 

The Daft patented process consists essentially in heating the 
rubber in contact with metal containing an alloy of antimony. 
When the rubber is to be attached to iron or steel the surface is 
electroplated with copper, zinc and antimony alloy. 

GAS PROOFING. 

Before india rubber reached its present value in the arts, 
and before coal gas was generally known as an illuminant, Mol- 
lerat obtained oil of caoutchouc by distillation and made a fine 
quality of illuminating gas from it. 

Vulcanized india rubber, whether compounded or pure, is 
permeable by gas. In making flexible gas tubing, therefore, it 
must be coated or in some way protected in order to make it gas 
tight. The common way of accomplishing this is to cover the 
rubber tube with an outer tube made of glue, glycerine, and bi- 
chromate of potash, this covering being protected in turn by a 
woven fabric. Another plan for accomplishing the same result 
is to have an outer and inner tube of india rubber, between the 
two being vulcanized a sheet of tin-foil. 

Pellen rendered india rubber impervious to gas by coating 
it with collodion mixed with a very small quantity of castor oil 
or with a varnish composed (1) of 32 per cent, of gum arabic, 
8 per cent, of sugar, and 60 per cent, of water, or (2) made from 
28 per cent, of dextrin, 60 per cent, of water, and 12 per cent, 
of gelatine. 

Bousfield rendered vulcanized india rubber impermeable to 
gas by applying linseed oil to it in the form of a varnish, the 
articles being heated. 

Gas Proofing for Balloons. — The following mixings are 
those approved by Churrel for gas balloons : 
For Gas-Tight Fabrics. 

Fine hard Para 87.00 

Paraffin (66 degrees C. ) . . . '. 0. 75 

Sulphur (twice sifted) 8.75 

Oxide of magnesia (twice sifted) 3. SO 

100.00 



262 MISCELLANEOUS PROCESSES 

For Tensile Strength. 

Fine hard Para 54.00 

Paraffin wax (66 degrees C.) 0. 50 

Carbonate of magnesia (twice sifted) 35.00 

Oxide of magnesia (twice sifted) 5 .00 

Fine sulphur 5.50 

100.00 
For Cold Vulcanized Gas-Tight Fabrics, 

Fine hard Para 98.75 

Paraffin wax (66 degrees C.) 1 .25 

100.00 
ACTION OF METALS ON RUBBER. 

The action of various metals on india rubber has always 
interested rubber manufacturers. In the memoirs and proceed- 
ings of the Manchester (England) Literary and Philosophical 
Society, 1890-91, William Thomson, F.R.C., and Frederick 
Lewis published an exceedingly interesting paper on this subject. 
They covered almost all of the metals that are likely in any way 
to come in contact with rubber surfaces, and proved what has 
long been acknowledged by rubber manufacturers : that the ac- 
tion of copper is most harmful. The metals that have no action 
at all on rubber are gold, silver, bismuth, antimony, arsenic, tin, 
chromium, iron, nickel, cobalt, zinc, and cadmium. Those that 
act only in a slight degree on rubber are lead, aluminum, pal- 
ladium, and platinum. 

Of the salts of metals that are very destructive, copper 
stands first, manganese oxides and nitrates of silver being, how- 
ever, almost as bad. Several other nitrates have also an injuri- 
ous effect, although not as much so as those just mentioned. 
They are the nitrates of ammonia, uranium, sodium, and iron. 

According to N. Foden, a well-known English expert, 
proofed goods in browns have caused him more trouble by 
deterioration than any other colors — more than black, even — and 
it is to be noted here that blacks as a rule are viewed with dis- 
trust by manufacturers, because it is believed generally that 
copper salts are used in the dyeing. Mr. Foden instances the 
time when brown tweeds were used largely, and when most 
manufacturers experienced a great deal of trouble with them, as 
the browns showed early signs of decay, while the grays remained 
soft and flexible. Mr. Foden suggests that, as certain dyers use 



SHRINKAGE OF RUBBER 263 

lime, which is cheaper than logwood, this may act destructively 
upon the rubber. 

Morgan holds that tackiness in crude rubber may be caused 
by salts of copper. His experiments with rubber latex and cop- 
per salts demonstrated that tackiness is produced in proportion 
to the copper salts present. 

Schidrowitz considers that tackiness is due to a physical 
change in the rubber molecule and not to a change in its chemi- 
cal composition. 

SHRINKAGE OF RUBBER. 
The following table shows the average rate of shrinkage in 
the various leading grades of india rubber, and also the widest 
range of shrinkage noted in the practice of some extensive manu- 
facturers. The figures express percentages in weight: 

Para sorts : Average Range 

Fine 16 to 18 15 to 20 

Medium 17 to 19 16 to 22 

Coarse 22 to 28 18 to 35 

Mangabeira 25 to 30 20 to 35 

Caucho 26 to 34 20 to 40 

Centrals 26 to 32 20 to 40 

Africans : 

Tongues 19 to 24 18 to 25 

Flakes 28 to 33 25 to 35 

Thimbles 22 to 28 15 to 35 

Accra sorts 24 to 32 20 to 40 

Congo sorts 19 to 24 18 to 35 

Benguela, sorts 16 to 20 16 to 20 

Mozambique sorts 17 to 28 10 to 35 

Madagascar sorts 30 to 40 25 to 55 

Assam 23 to 31 8 to 45 

Borneo 33 to 38 30 to 45 

Mr. T. Bolas, in his "Cantor lectures" on india rubber, in 

1880, gave the following estimates of shrinkage of these leading 

grades : 

Para 15 per cent. 

Para negroheads 25 

Ceara 28 

Guayaquil 40 

Borneo 25 

African ball 25 

African tongues 35 

African niggers 25 

Madagascar 25 

PARA RUBBERS. 

The next table indicates in detail the percentage of shrink- 



264 MISCELLANEOUS PROCESSES 

ages in the various grades of Para rubber, also determined by the 
practice of American manufacturers : 

Fine Medium Coarse 

Bolivian 15 to 17 16 to 18 20 to 25 

Mollendo 15 to 17 16 to 18 

Madeira 15 to 18 16 to 19 20 to 25 

Manaos 16 to 17 17 to 18 18 to 22 

Upriver 16 to 18 17 to 19 18 to 25 

Matto Grosso 16 to 18 17 to 19 20 to 28 

Angostura 16 to 18 17 to 19 25 to 30 

Caviana 16 to 18 18 to 20 25 to 30 

Itaituba 17 to 18 18 to 19 20 to 25 

Islands 18 to 20 18 to 22 25 to 35 

Cameta 30 to 35 

The shrinkage of Mangabeira (Pernambuco) thin sheet is 
about 25 to 30 per cent. ; thick sheet, 30 to 35 ; ball, 20 to 25. 
Caucho (Peruvian) slab, 30 to 40; sheet, 30 to 35; strip, 25 to 
35 ; ball, 20 to 25. 

The better grades of centrals shrink from 25 to 30 per cent. ; 
other grades, generally from 30 to 40. 

AFRICANS. 

The Gold Coast sorts (including Accra, Cape Coast, Salt- 
pond, Addah, Quittah, and Axim) range about as follows: but- 
tons or biscuit, 20 to 30 ; flake, 30 to 35 ; lump, 30 to 40 ; niggers, 
20 to 35. 

Cameroon ball, 18 to 25 ; clusters, 18 to 28. 

Lagos buttons, 25 to 35; lump, 30 to 40; strip, 25 to 35. 

Congo buttons, 25 to 30; ball No. 1, 20 to 25 ; ball No. 2, 
25 to 35 ; Upper Congo ball and strips, 20 to 35 ; red ball, 18 to 
22; Equateur small ball, 16 to 20; mixed ball, 18 to 22; Lopori 
small ball, 16 to 22; Kassai black twist, 18 to 22; red twist, 20 
to 25 ; ball, 20 to 25. 

Benguela (and Loanda) sausage, 16 to 20; niggers, 18 to 20. 

Mozambique (including Lamu) ball No. 1, 10 to 15; ball 
No. 2, 15 to 25 ; ball No. 3, 25 to 35 ; sausage, 20 to 35. 

Madagascar pinky, 30 to 35 ; Majunga, 30 to 35 ; black, 30 
to 40 ; niggers, 30 to 40. 

EAST INDIAN. 

Assam No. 1, 10 to 15 ; No. 2, 20 to 30; No. 3, 30 to 35. 
Penang, No. 1, and Java No. 1, 10 to 15 per cent.; other 
numbers same shrinkage as Assam. 



SHRINKAGE OF RUBBER 265 

E. Chapel gives this table of percentage of shrinkage: 

Para, fine 12 Ceara 28 

Para, coarse 25 African ball 28 

Loando 17 Madagascar 28 

Colombia . . 20 Assam 28 

Java 22 Gaboon 35 

Gambia 24 Borneo 35 

TO FIGURE SHRINKAGE IN CRUDE RUBBER. 

It is strange that there should be a divergence of opinion 
and method in arriving at the net cost of rubber after washing, 
sheeting, and drying it, yet such is the case. To assist those who 
have not studied this question, the right and the wrong way of 
figuring on shrinkage is given here. Take, for instance, an 
average-priced rubber: 

Example A. 
100 lbs. rubber at $0.50 = $50.00 
20 lbs. shrinkage = 20 per cent., or l-5th. 



80 lbs., net cost $50.00, as above. 
80 ) 50.00 ( 62.50 
48 

200 
160 

400 
400 

Some persons, however, figure in this way: 

Example B. 

100 lbs. at $0.50 lb. 

Shrinkage 20 per cent. = l-5th. 

$0.50 -f- 1-Sth (10 cents) = 60 cents. 

Example A. — Correct method — net cost $62.50 

Example B. — Incorrect method — net cost 60.00 



Difference $2.50 

This is a difference of 4 per cent., which, if it occurs in manu- 
facturing a large amount of goods where rubber is the greater 
part of the compound, would make quite a difference in the profit. 

SPECIFIC GRAVITY OF RUBBER. 

The following records of the specific gravities of different 

samples of india rubber have been collected: 

Best Para, taken in dilute alcohol (Ure) 0.941567 

Best Assam, taken in dilute alcohol (Ure) 0.942972 

Best Singapore, taken in dilute alcohol (Ure) 0.936650 



266 MISCELLANEOUS PROCESSES 

Specific gravity of rubber {Continued) : 

Best Penang, taken in dilute alcohol (Ure) 0.919178 

Caoutchouc (Julian) 0.920000 

Crude caoutchouc of India (Adriani) 0.966800 

Black caoutchouc (Adriani) 0.945200 

Prepared from juice in pure state (Faraday) 0.925000 

Determined by E. Soubeiran 0.935500 

Determined by Payen 0.925000 

Faraday's general analysis of the latex of the Hevea is : 

Caoutchouc 30.70 

Albuminous extractive and saline matter 12.93 

Water 56.37 

The specific gravity of the latex quoted was 1.012. 
The crude rubber itself is made up of the following general 
composition: carbon, 87.5; hydrogen, 12.5. 

PUNCTURE FLUIDS AND TIRE FILLERS. 

Campbell's and Cush man's Puncture Fluid. — A mix- 
ture consisting of : water, 2 quarts ; granulated cork, 4 ounces ; 
powdered cork, 2 ounces; French chalk, 1 pound; white lead, 8 
ounces; and gum arabic, 2 ounces. Canadian patent. 

Cyco is a popular compound, said to serve as a preserver of 
tires as well as healer of tire wounds. It is made of vegetable 
gums that will not harden; neither will it interfere with vul- 
canizing in the event of a large rupture. 

Dow's Inner Tube Filler. — A mixture of paste and 
feathers held in a continuous pocket that covers the tread of the 
inner tube. 

Elastes. — An English compound made of glue, glycerine, 
and chromic salts. 

Everlastic is a substitute for air, and by some considered 
a good compound. As a liquid it is forced into the tire until 
the desired pressure is reached, and in a comparatively short 
time it solidifies and is said to become like rubber. It is not 
affected by heat or cold. 

Fagioli, under a British patent, produces a composition con- 
sisting preferably of these proportions: 1 pint giant cement, 
\y 2 pints of rubber solution, and 2 T / 2 gallons granulated cork. 

Frankenburg's Puncture Fluid. — Made of dead Borneo, 
oxidizable vegetable oil, and sulphur; a British patent. 



PUNCTURE FLUIDS AND TIRE FILLERS 267 

Inrig, under a British patent, prepares a rubber substitute 
from the gelable portions of animals. Fifty parts of such ma- 
terial are treated with SO parts of water and from 20 to 60 parts 
of oil at a temperature of 200 degrees F. Subsequently sodium 
stannate and potassium bichromate are added. On heating to 
212 degrees F. a mass is obtained which may be set in a mold 
and used for filling motor tires. 

Newmastic. — A tire filler, the component parts of which 
are a secret, but which is apparently of the glue and glycerine 
type. 

Puncture Closer. — A British compound: 10 parts gutta- 
percha, 60 virgin wax, 5 tallow, 20 rosin, 5 wild thyme. 

Roland's Puncture Compound. — Glue and glycerine, to 
which is added sugar or molasses. 

Rubber Foam or Cellazote is the invention of an Aus- 
trian engineer, Fritz Pfleumer, of Dresden, Saxony. It is being 
used successfully as a filling for automobile tires in war service 
under the name of "Cellazote," thus displacing inner tubes. The 
material consists of pure rubber in a remarkably soft, spongy 
state. Its manufacture is based upon the observation that rubber 
as well as gutta-percha and balata are not homogeneous or im- 
penetrable substances, but represent a microscopic reticular struc- 
ture into which gas can penetrate and remain under certain con- 
ditions. Rubber foam can be produced either in the form of 
soft rubber or in the form of hard rubber. 

To make soft rubber foam, rubber is subjected in an auto- 
clave to the high pressure (80 to 300 atmospheres) of an op- 
tional gas (nitrogen) and is vulcanized. Under the high pres- 
sure the gas penetrates the rubber so that when vulcanization is 
sufficient and the gas pressure removed the rubber thus treated 
swells into a foam-like mass, the volume of which is from 13 
to 18 times that of the original rubber before treatment. This 
foam-like mass is made up of a multitude of closed cells, each 
of which contains, under pressure, a portion of the gas that was 
forced into the rubber during the vulcanization. The size of 
these cells and the pressure of the gas they contain can be varied 
indefinitely by manipulations of the manufacturing process. For 
making hard-rubber foam the process is continued by placing the 



268 MISCELLANEOUS PROCESSES 

soft-rubber foam in iron retorts and subjecting it to heat and 
pressure, continuing the vulcanization until the desired degree 
of hardness is obtained. The shape and conformation may also 
be equally varied. 

It is very light (about 100 pounds per cubic yard of vol- 
ume), is both gas- and water-proof and affected only by strong 
acids. The cost of production varies with the price of crude 
rubber, and is rather higher than the final cost of good soft or 
hard rubber. One pound of rubber foam has the same volume 
as 18 pounds of solid rubber. 

A variety of practical applications is claimed for rubber 
foam, due to its bulk and cellular structure. The list includes 
its use as a substitute for cork in life belts; filling for pneu- 
matic tires and playing balls, imparting resiliency regardless of 
punctures ; insulation of heat and cold in clothing for autoists 
and aviators and in walls of refrigerators ; also for upholstery 
and other cushioning purposes. 

While not affected by acids generally, rubber foam will dis- 
solve in ammonia, which can be used to soften hard 'foam to 
facilitate working it. When the ammonia is evaporated hard 
foam regains its original hardness. It is said to be susceptible of 
fireproofmg. 

Rubberine. — A special solidifying liquid tire filler made in 
England, very largely used for filling the tires of armored cars, 
lorries, kitchen cars, and ambulances of the Entente Allies, for 
service on the battlefields of the Great War. An interesting 
point is that pneumatic tires returned from the front for refill- 
ing, although riddled with shrapnel bullets, had served their pur- 
pose until the car got safely back to its base. 

Scott's Puncture Fluid. — Fifty parts milk, 17 parts isin- 
glass, 200 parts gelatine, 10 parts carnauba wax, 3 parts formal- 
dehyde, 1 part gum ammoniacum. Of British origin. 

Suber's Filler. — One ounce carnauba wax, T / 2 ounce gum 
tragacanth, x / 2 ounce water. Add glue and mix in steam. 

Tire Life. — A tire filler of the glue and glycerine kind. 



CHAPTER XV. 

SYNTHETIC RUBBER. 

The researches on the chemical constitution of caoutchouc, 
or rubber, and the sources and processes available for its syn- 
thesis, have been outlined by B. D. W. Luff in the "Journal of 
the Society of Chemical Industry" (October 16, 1916). The 
author's paper may be summarized as follows: 

Between 1835 and 1840 the study of caoutchouc was under- 
taken on scientific lines by various investigators, including Dal- 
ton, Liebig, Himly, A. Bouchardat, and Gregory, but in all cases 
their work was more or less disjointed. The most systematic 
attempt to isolate and examine the various products present in 
the crude distillate from caoutchouc was made by Greville Wil- 
liams in 1860. He obtained (1) a liquid boiling at 37 degrees 
C. to which he gave the name "Isoprene"; (2) a large propor- 
tion of a hydrocarbon boiling at 170 to 173 degrees C, which 
was identical with a body previously obtained by Himly, and 
called caoutchoucine — this has since been proved to be dipen- 
tene; (3) a fraction boiling above 300 degrees C, to which he 
gave the name "Heveene." 

Gustave Bouchardat in 1879 undertook a detailed investiga- 
tion of isoprene, in the course of which he examined the action 
of hydrochloric acid. He noted that an additional product was 
formed, but under certain conditions the action of the acid re- 
sulted in the formation of a solid mass, not containing chlorine, 
but having, in fact, the same percentage composition as isoprene 
itself. ,He described this body thus: "It possesses the elasticity 
and other properties of rubber itself. It is insoluble in alcohol, 
swells in ether and also in carbon bisulphide, in which it dis- 
solves after the fashion of natural rubber." He also noted that 
on distillation it yielded the same hydrocarbon as in the case of 
the natural product. This was an important step in the synthesis 
of caoutchouc; in fact, in order to make this complete, all that 
was necessary was to prepare isoprene from elementary materials. 
At that time the only source of isoprene was rubber itself. 

269 



270 SYNTHETIC RUBBER 

Bouchardat's results were confirmed in 1882 by Tilden, who 
observed the polymerization of isoprene. In discussing isoprene 
he remarked that one of its chief characteristics was its conver- 
sion into true caoutchouc when brought in contact with certain 
chemical reagents. He pointed out that this was of great prac- 
tical interest as, if isoprene could be obtained from some other 
and more accessible source, the synthetical production of rubber 
could be accomplished. Two years later he succeeded in obtain- 
ing isoprene by passing the vapors of turpentine through a hot 
tube. 

The outcome of the work of these two investigators was that 
the caoutchouc molecule was shown to be formed by the union 
of a number of molecules of isoprene, and this union or poly- 
merization could be brought about by treating the isoprene with 
suitable reagents. To them must be given the major share of the 
credit for laying the foundation of the numerous processes since 
suggested for preparing synthetic rubber. 

In 1887 Wallach observed that isoprene undergoes polymeri- 
zation on exposure to light with production of a rubber-like 
mass. In 1892 Tilden showed that the material obtained in this 
manner could be vulcanized with sulphur. The synthesis of 
isoprene, and as a corollary, that of caoutchouc, was accom- 
plished by Euler in 1897. 

In 1909, owing to the rapid rise in the price of rubber, the 
problem was taken up in England in a systematic manner by 
Perkin, Fernbach, Weizmann and Mathews and in Germany 
by the Bayer and Badische companies. In 1884 Tilden suggested 
that not only isoprene, but its homologs, should be capable of 
polymerization in a similar manner. This was found to be the 
case, and these bodies, chief among them butadiene, form the 
basis of methods for obtaining synthetic caoutchoucs. 
PRESENT STATUS OF SYNTHETIC RUBBER PRODUCTION. 

Dr. F. W. Hinrichsen, in the "Zeitschrift des Vereines 
Deutscher Ingenieure," discusses the present situation in regard 
to the synthetic production of rubber or caoutchouc. There is 
not to-day the enthusiastic interest in the matter that existed a 
few years ago, although it is one of great scientific importance. 

Dr. Hinrichsen in his review confines himself to the essen- 



RUBBER FROM IS OP RENE 271 

tials of the problem, observing that a complete history of its 
development is impossible, because only a small part of the work 
done along this line in commercial laboratories has come to the 
attention of the public. 

Harries in 1905 determined the chemical constitution of 
natural rubber, C 10 H 16 , as that of a 1.5 dimethylcyclo-octane of 
the formula 

CH 3 — C CH 2 CH 3 CH 

CH CH 2 CH 2 C— CH 3 

In 1909 Dr. Fritz Hofmann and Dr. Carl Coutelle, chemists of 
the Elberfeld Dye Works, devised a process for absolutely pure 
isoprene and were the first to convert it into rubber by simply 
heating it in a closed tube separately or in the presence of certain 
other substances. A sample of this rubber was sent to Harries, 
who proved chemically with absolute certainty that it actually 
was rubber. As the method of Hofmann and Coutelle was not 
then publicly known, Harries took up experiments to trans- 
form isoprene into rubber. In a lecture in Vienna in 1910 he 
reported his observation that it was possible to convert isoprene 
into rubber by heating in a closed tube in the presence of glacial 
acetic acid. Harries deserves credit for thus publishing a method 
which could be repeated by others. 

Creditable work in the technical development of the problem 
was done by numerous individual German and other scientists, 
by the Elberfeld Dye Works and by the Baden Aniline & Soda 
Works. In the original patent specification of the Elberfeld Dye 
Works the inventors did not confine themselves to the use of 
isoprene as the basic material, but included the use of a series 
of hydrocarbons of similar composition and behavior toward 
polymerization, namely hydrocarbons with a so-called system of 
conjugated double bonds, such, for example, as erythrene and 
dimethylbutane and many other similarly constructed substances. 

On account of the differences in the basic material there was 
a possibility of obtaining a series of different rubbers which 
naturally differed in their chemical constitution. It was also 
found that the process of polymerization was capable of modifi- 
cations and that the rubbers obtained by employing different 
methods with the same basic substance varied among themselves. 



272 SYNTHETIC RUBBER 

It was thus observed independently by Harries and the Eng- 
lish investigators, Mathews and Strange, that polymerization in 
the presence of metallic sodium proceeds at great velocity and 
the resulting rubber differs materially in its properties from that 
produced by mere heating. The chemists of the Baden Aniline 
& Soda Works found that if polymerization by sodium is car- 
ried on in an atmosphere of carbonic acid the results are dif- 
ferent. A further process worked out by the same company is 
based on the use of ozonizers on peroxide as catalyzers. 

Thus various rubbers may be obtained differing from each 
other in their properties according to the nature of the prime 
materials and the method of polymerization. The following com- 
pilation, according to Holt, is a concise resume of a series of 
such differing rubber-like substances. 

RUBBERS FROM BUTANES. 

Standard Rubber (by heating) — Easily soluble, elastic and 
capable of being vulcanized. 

Ozonide Rubber. — Insoluble, strongly inflatable, very elas- 
tic, not capable of being vulcanized. 

Carbonic Acid Rubber. — Not soluble, not inflatable, mod- 
erately elastic, not capable of being vulcanized. 

Sodium Rubber. — Easily soluble, elastic, capable of being 
vulcanized. 

RUBBERS FROM ISOPRENE. 

Standard Rubber. — Easily soluble, elastic, capable of being 
vulcanized. 

Ozonide Rubber. — Soluble only after calendering, strongly 
inflatable, elastic, capable of being vulcanized. 

Carbonic Acid Rubber. — Insoluble, not inflatable, elastic, 
capable of being vulcanized. 

Sodium Rubber. — Easily soluble, not elastic, can be vul- 
canized incompletely and only with difficulty. 

RUBBERS FROM DIMETHYL BUTANES. 

Standard Rubber. — Easily soluble, not elastic, capable of 
being vulcanized as hard rubber only. 

Ozonide Rubber. — Soluble only after calendering, inflat- 
able, not elastic, can be vulcanized as hard rubber only. 



UTILITY OF SYNTHETIC RUBBERS 273 

Carbonic Acid Rubber. — Insoluble, not inflatable, not elas- 
tic, can be vulcanized only with difficulty and is easily oxidized. 

Sodium Rubber. — Soluble and insoluble modifications, in- 
elastic and incapable of vulcanization. 

This possibility of obtaining substances of varying properties 
by changing the basic materials and the process of polymeriza- 
tion gave rise to the hope of producing at will rubbers with 
properties adapted to special applications, somewhat as in the 
dyestuffs industry colors are modified at will. The commercial 
importance of rubber synthesis depends on the product equaling 
natural rubber in two respects, price and practical applicability. 

The price factor depends in the first instance on the manu- 
facturing cost of the hydrocarbons of the isoprene series which 
are used as the basic materials. 

Progress has been made in this field by the Baden Aniline & 
Soda Works, which starts with certain fractions of petroleum. 
Other available substances are starch, amyl alcohol, turpentine, 
acetylene, etc. With all the processes there are such large quan- 
tities of by-products that their removal or utilization would con- 
stitute a problem even more difficult than that of the production 
of the rubber itself. At present there is no possibility of serious 
competition of artificial with plantation rubber as regards price. 

As regards practical utility synthetic rubbers seem to lack 
the durability of natural rubber because the latter, by its vege- 
table origin, contains a series of associated substances, resins, 
albumen, etc., which undoubtedly have an influence on its dura- 
bility, for it is well known that deresinated rubber is much more 
easily attacked by the oxygen of the air than rubber containing 
resin. Possibly these associated substances act as protective 
colloids which reduce the vulnerability of the pure substance. 

A further reason why synthetic rubbers are inferior to 
natural rubber in mechanical properties is that the former are 
not uniform substances, but mixtures. According to recent in- 
vestigations of Steimmig, in the oxygen splitting of synthetic 
rubbers there appears in addition to coulinie acid and coulinie 
aldehyde (which, according to Harries, correspond to natural 
rubber), resinous acid and acetonyl-acetone. 

The two last-mentioned substances indicate that in the poly- 
merization of isoprene, in addition to the 1.5-dimethylcyclooc- 



274 SYNTHETIC RUBBER 

tanes, a smaller amount (20 per cent.) of the 1.6 compound must 
have been formed by abnormal condensation, which, upon being 
split by means of ozone, furnishes the two components men- 
tioned. The latter have never been found in natural rubber. 
Until possible to arrange the conditions of polymerization so 
that the synthetic rubbers will constitute uniform compounds, 
it is not to be expected that synthetic rubbers will equal natural 
rubber in its useful properties. 

Synthetic rubber has been attained as a triumph of chemical 
science and the researches have been a great contribution to our 
knowledge. Nevertheless, synthetic rubber is not an industrial 
success, even in Germany under the stimulus of imperative war 
needs. 

Therefore the following cautions on the subject may still 
have practical value : 

Every year there is more or less newspaper prominence 
given to synthetic rubber discovery and discoverers, but so far 
absolutely nothing has been accomplished commercially. The 
producers of alleged synthetic rubber work along a variety of 
lines. There is, first and most dangerous, the line of fraud, 
where real rubber disguised is put forth as a cheap synthetic 
production. This procedure has been the means of extracting 
many dollars from the pockets of the credulous. There is an- 
other class of honest but somewhat ignorant inventors who make 
products that in some respects are similar to rubber, and which 
they believe are equal to or even better than rubber. They use 
oils, gums, cellulose, in fact, almost anything that will produce 
a waterproof plastic. These products are often of value in con- 
nection with rubber and sometimes when used alone, but never 
yet have anywhere near equaled the crude material. 



,[ CHAPTER XVI. 

VULCANIZATION WITHOUT SULPHUR. 1 

From its inception the world's rubber industry has depended 
upon sulphur to effect vulcanization. The possible advantages to 
be derived from a practical method of vulcanization without sul- 
phur are to be found in freedom from "blooming" or "sulphuring 
up" of the goods, deterioration on aging due to excess of sulphur 
and the possibility of using as pigments colors not permanent in 
the presence of sulphur. The Russian chemist, Ivan Ostromi- 
slensky, of Petrograd, has conducted extensive researches on vul- 
canization without sulphur, and is the inventor of a number of 
processes on the subject. The following pages embrace his pub- 
lications on the problem: 

The hot vulcanization of caoutchouc discovered by Good- 
year (1839) proceeds, as is well known, under simple condi- 
tions; a homogeneous mixture of caoutchouc and sulphur is 
heated at 130 to 145 degrees C. As a result, the initial caout- 
chouc loses its plasticity, and separate pieces of fresh, fractures 
no longer exhibit the power of adhesion. The solubility is low- 
ered, and the "interval of elasticity" increased; the fatal tem- 
perature of well vulcanized natural caoutchouc lies at about — 35 
degrees, that of the chemically pure product being about — 18 
degrees. What takes place during the heating of the caout- 
chouc? Attempts to explain this peculiar process have exhausted 
all the theoretical possibilities. Some investigators regard it as 
an exclusively physical process, and others as solely a chemical 
reaction, while many authors consider vulcanization to be deter- 
mined by both physical and chemical changes. 

Since all phenomena, at any rate, of unorganized nature, are 
divided into only two groups — the physical and the chemical — 



1 "Mechanism of the Process of Vulcanization of Caoutchoucs," by 
Ivan Ostromislensky, in the "Journal of the Russian Physico-Chemical 
Society," 1915, pages 1,453-1,461. Translated by Thomas H. Pope, B.Sc. 
Translation revised by Dr. H. P. Stevens, published in the "India Rub- 
ber Journal," September 30, 1916. 

275 



'276 VULCANIZATION WITHOUT SULPHUR 

there can be no essentially new theory of vulcanization. Never- 
theless, the nature of the mechanism of the process even yet 
remains unexplained. 

The supporters of Weber's chemical theory regard vulcan- 
ized solid caoutchouc (ebonite) as a polymeride of the com- 
pound, C 10 H 16 S, (16 per cent, of sulphur), while others, for in- 
stance, Erdmann, consider it to be the thiozonide, C 10 H 16 S 3 , or 
even a dithiozonide. On the other hand, many identify the vul- 
canization of caoutchouc with the process of "swelling" of col- 
loids or that of gelatinization or adsorption, that is, with the 
processes of formation of solid or semi-solid solutions. 

Some of the supporters of the "mixed" theory consider that 
the sulphur itself swells or is adsorbed or dissolved in the free 
caoutchouc, whereas other authors assume the preliminary for- 
mation of a compound of the caoutchouc with the sulphur — 
although only in insignificant amount — this compound being then 
adsorbed in the still unchanged caoutchouc. 

I shall not devote time to the extensive literature of this 
question, but shall proceed immediately to the conclusions which 
result from my observations and my new methods for vulcaniz- 
ing caoutchouc. 

Until now no method of vulcanizing caoutchouc has been 
known in which any organic or mineral compound not contain- 
ing sulphur is used as vulcanizing agent. 2 But the chemical and 
especially the physical theories of vulcanization anticipate the 
possible existence of a whole series of such compounds. I de- 
cided to attempt to find substances which may replace sulphur 
in the vulcanization of caoutchouc. 

It was thought that the investigation of the action of homo- 
logs and analogs of such substances on caoutchouc and that 
of the external conditions of the new process — the influence of 
different admixtures, accelerators, etc. — might elucidate the 
mechanism of vulcanization itself. 

This task has now been completed, and two new methods for 
the hot vulcanization of caoutchouc have been discovered. 



2 The process of vulcanization is often termed the sulphuring of 
caoutchouc. Vulcanization by calcium or sodium hypochlorite or free 
hypochlorous acid, like vulcanization by hologens (bromine, iodine, or 
iodine bromide), leads, as is known, only to "horny" rubber, i.e., to ebon- 
ite-like substances. Compare Marckwald and Frank, "Uber Herkommen 
und Chemie des Kautschuks," Dresden, page 62. 



TRINITROBENZENE 277 

When heated with unsaturated hydrocarbons, sulphur pro- 
duces a twofold effect: it combines at the double bond with 
formation of thiozonides (Erdmann), or it oxidizes the ethylene 
grouping, removing hydrogen in the form of hydrogen sulphide, 
a new ethylenic derivative, or a new compound containing sul- 
phur being thus formed. 3 

On the physical side, sulphur is characterized besides by the 
oidinary constants (specific gravity, melting point, etc.), and by 
its ability to exist in different polymorphic modifications (rhom- 
bic, hexagonal, amorphous, etc.). 

In searching for organic substances which vulcanize caout- 
chouc, like sulphur, the first to be investigated are those which 
resemble sulphur in oxidizing ethylenes, and at the same time 
are able to unite at the double linking. Of the physical constants 
of such substances the essential ones are the melting point and 
the vapor pressure at the temperature of vulcanization ; after 
these, the solubility in caoutchouc, specific gravity, etc. Besides 
possessing physical constants near to those of sulphur, the 
sought-for compounds should exist in polymorphic modifications. 
This explains why, in this investigation, I first of all made 
a halt at compounds containing the nitro-group. These oxidize 
organic substances {e.g., in Skarup's synthesis of quinoline), 
and at the same time readily combine with various ethylenes 
(attention may be called to the compounds of Ar (N0 2 ) with 
polycyclic hydrocarbons and to the author's use of tetranitro- 
methane as a reagent for double bonds). 

1 :3 : 5-Trinitrobenzene has melting point, 118 degrees C, 
very near to that of sulphur, i.e., below the temperature of vul- 
canization, and in specific gravity it also resembles sulphur. 
Further, most polynitro-compounds exist in polymorphic modifi- 
cations. 

1:3: 5-Trinitrobenzene was the first instance which I 
hoped would serve as a substitute for sulphur in vulcanization. 
Experiment completely confirmed my expectation. It was found 
that both synthetic and natural caoutchoucs are vulcanized more 
rapidly and easily by various nitro-compounds than by sulphur 
itself under the same conditions. The result was a product pos- 
sessing all the associated physical properties of caoutchouc vul- 
canized by means of sulphur. Experiments were made with both 



3 When acenaphthere is heated with sulphur, the hydrocarbon G 6 H 1S 
(decacyclene) is formed. 



278 VULCANIZATION WITHOUT SULPHUR 

fatty and aromatic nitro-compounds, and vulcanization took 
place with nitrobenzene, dinitrobenzenes, trinitrobenzenes, tri- 
and tetra-nitronaphthalenes, picric acid, picramic acid, picryl 
chloride, "artificial musk," nitro-cyclohexane, and many other 
compounds. 

Further investigation showed that the vulcanizing properties 
of nitro-compounds do not depend on their capacity for combin- 
ing at the double linking. As is well known, picric acid com- 
bines with ethylenic compounds considerably more readily than 
most other nitro-compounds of the aromatic series, and yields 
more stable products. Next in order come picryl chloride, pic- 
ramic acid, trinitrobenzene, etc. ; dinitro- and mononitro-ben- 
zenes do not unite at all with ethylenic derivatives. 

On the other hand, according to their vulcanizing power, 
nitro-compounds are arranged in the reverse order, or more 
accurately, in an order which reveals no analogy between the 
processes of vulcanization and of combination at the double link- 
ing. 

Caoutchouc is vulcanized more rapidly and easily by 1 : 3 : 5- 
trinitrobenzene, after which come dinitrobenzene, mononitroben- 
zene, tetranitronaphthalene. Picric acid and picryl chloride do 
not yield satisfactory products ; vulcanization undoubtedly be- 
gins, but, in spite of many series of experiments, I have never 
succeeded in bringing it to completion; the caoutchouc partially 
retains its plasticity, and sticks when fresh fractures are pressed 
together. Mononitrobenzene, however, gives completely satis- 
factory results. 4 

The combining capacity of nitro-compounds increases with 
the number of nitro-groups in the molecule, but we are con- 
vinced that the vulcanizing power of nitro-compounds does not 
depend on this cause. Ostromislensky found that tetranitro- 
methane unites with ethylenic compounds of both the aromatic 
and aliphatic series, but in no case has it been possible to vul- 
canize caoutchouc with tetranitromethane, although a large num- 
ber of attempts have been made. 

Various other substances which, like nitro-compounds, are 
able to unite with ethylenic derivatives, have also been tried, 



4 Slight adhesion between freshly cut surfaces, as is well known, 
does not indicate that vulcanization is incomplete, especially with rubber 
which has been only recently vulcanized. — H. P. S. 



BENZOL PEROXIDE 279 

among them triphenylmethane and diaminotriphenylmethane. 
These compounds, in perfect agreement with the above results, 
cause no trace of vulcanization, the caoutchouc remaining sticky 
and plastic, and retaining even its pale color. 5 These facts show 
that the power of nitro-compounds to vulcanize caoutchouc is 
not determined by their ability to combine with ethylenes. 

Is any role in the vulcanization played by the capacity of 
nitro-compounds to oxidize organic substances — by their prop- 
erty of yielding active oxygen with formation of nitroso-com- 
pounds? In other words, does the vulcanizing action of nitro- 
compounds depend on the combination of active oxygen at the 
double linking of the caoutchouc? This question must, as ex- 
periment shows, be undoubtedly answered in the affirmative. 
First of all, nitroso- and isonitroso-compounds do not vulcanize, 
as is shown by experiments with nitrosobenzene and isonitroso- 
camphor under various conditions. This result leads to the 
assumption that the vulcanizing power of nitro-compounds be- 
longs to one of the oxygen atoms of the N0 2 radicle. It follows, 
therefore, that under suitable conditions caoutchouc should be 
vulcanized by ozone or ozonides, or by various peroxides, per- 
acids, etc. 

This fundamental conclusion has been confirmed by direct 
experiment, a second new method having been found for the 
hot vulcanization of caoutchouc by compounds containing active 
oxygen. Special attention has been paid to the vulcanization of 
natural and synthetic caoutchoucs with benzoyl peroxide and per- 
benzoic acid. It is found that caoutchouc is vulcanized by ben- 
zoyl peroxide incomparably more rapidly and easily than by sul- 
phur or even nitro-compounds. 

In order to confirm the deciding part played by the oxygen 
atom, attempts were made to vulcanize caoutchouc with barium 
peroxide. This substance yields its oxygen with moderate rapid- 
ity only at very high temperatures, and should not effect vul- 
canization 6 if the latter is determined by the combination of 



5 This again is not necessarily an indication that vulcanization has 
not taken place. — H. P. S. 

6 It has been already found that the melting point of vulcanizing 
substance does not affect the process. Thus, caoutchouc is readily vul- 
canized by nitrobenzene, which is a liquid, and by tetranitronaphthalene, 
which melts at 218 degrees, whereas the vulcanization proceeds at 116-145 
degrees C. 



280 VULCANIZATION WITHOUT SULPHUR 

oxygen at the double linking of the caoutchouc. Actual experi- 
ment gives the results expected, since barium peroxide produces 
no trace of vulcanization. 

These new methods of vulcanizing caoutchouc, and the 
favorable results obtained, are of undoubted scientific and prac- 
tical interest, and in the first place throw new light on the puz- 
zling mechanism of this process. 

We are convinced that the present day vulcanization of 
caoutchouc begins with a chemical process. Only certain classes 
of substances — sulphur and some of its derivatives (S, Cl 2 , 
Ca S 5 .), nitro-compounds, peroxides and per-acids — bring about 
vulcanization. The physical constants and peculiarities of the 
vulcanizing substances are without influence on the final effect. 
What can there be common to the physical properties of gaseous 
oxygen, sulphur, tetranitronaphthalene and perbenzoic acid? At 
the same time it is sufficient to replace the oxygen of dinitrotri- 
phenylmethane by hydrogen or to remove from the nitro-group 
of nitro-benzene one atom of oxygen, to obtain a compound — 
diaminotriphenylmethane, nitrosobenzene — absolutely devoid of 
the power to vulcanize caoutchouc. 

In the process of vulcanization, chemical reactions are al- 
lotted, therefore, a definite but still quite modest place. Chemical 
action with the vulcanizing compound occurs with only a negli- 
gible fraction of the initial caoutchouc. Thus, it is found that 
the complete vulcanization of 100 parts of natural Para caout- 
chouc requires only 0.5 part of nitrobenzene or 1 : 3 : 5-tri- 
nitrobenzene. 

There can be no question here of molecular proportions, 
since 100 parts of C 10 H 16 would correspond with a minimum of 
156 parts of Q H 3 (N0 2 ) 3 . Even if it is assumed that C 10 H 10 
requires only one atom of active oxygen — which is not true — 
and that the molecule of trinitrobenzene contains three atoms 
and that of nitrobenzene one atom of active oxygen, 100 parts 
of caoutchouc would require 52 parts of trinitrobenzene or 90 of 
nitrobenzene. Even the corresponding solid ebonite is, however, 
obtained by vulcanizing rubber in presence of 10-15 per cent, of 
trinitrobenzene. 

Thus, with the actual method for vulcanizing caoutchouc 
only a vanishing part of the latter enters into chemical reaction, 



PHASES OF VULCANIZATION 281 

but this reaction is actually indispensable. The further course 
of this interesting process is conditioned by physical interaction 
between the vanishing quantity of caoutchouc which has reacted 
and that which has remained unchanged. 

Thus, we arrive at the conclusion that the vulcanization of 
caoutchouc is divided sharply into two fundamental phases : ( 1 ) 
A chemical reaction affecting only an insignificant part of the 
caoutchouc, and (2) adsorption or swelling of the unchanged 
caoutchouc into the product of this chemical reaction. 

Vulcanization may, however, be imagined as an exclusively 
physical process, since theoretically it may begin with the second 
phase of the process. Thus, instead of bringing nitro-compound, 
sulphur, or peroxide into contact with caoutchouc, we may iso- 
late and make use of the minute proportion of substance formed 
in our first phase; by heating this mixture we should undoubt- 
edly obtain vulcanized caoutchouc. In such case vulcanization 
takes place in a single phase — adsorption or swelling of the 
initial caoutchouc into the mixed product, and represents an ex- 
clusively physical process typical of caoutchouc. In vulcaniza- 
tion by means of sulphur the existence of the latter in the free 
state is of no importance, as it is necessary only for the prelimi- 
nary formation of its compound with caoutchouc, and then only 
in negligible amount. 7 

The elastic and other properties of caoutchouc vulcanized, 
for instance, by trinitrobenzene, are qualitatively and quantita- 
tively identical with those of caoutchouc vulcanized with sulphur. 
Both substances are devoid of plasticity and stickiness and ex- 
hibit similar difficult solubility, etc. 

Only by chemical analysis might these two vulcanizates be 
distinguished, although they are obtained by treatment of caout- 
chouc by absolutely different compounds. The nature of the vul- 
canizing substances is, therefore, almost without influence on the 
physical properties, solubility and all the elastic properties of the 
resulting caoutchouc; it has, further, no effect on the chemical 
properties of the vulcanizate, since the latter contains only a 
negligible proportion of foreign substance. 

It may again be emphasized that the characteristic changes 



T It may be that this compound vulcanizes caoutchouc only when in 
'statu nascendi." 



282 VULCANIZATION WITHOUT SULPHUR 

in the properties of caoutchouc produced by vulcanization are 
determined exclusively by a physical process — the adsorption or 
"swelling" of the caoutchouc. 

These new methods of vulcanization of caoutchouc open up 
a wide perspective, and it may be that the nitro-compounds, per- 
oxides and per-acids represent only the "first swallow" and that 
further work will reveal sooner or later other quite diverse sub- 
stances capable of vulcanizing caoutchouc like sulphur. 8 

Further investigation of this method of vulcanization 9 shows 
that natural Para caoutchouc is completely vulcanized by as little 
as 0.5 per cent, of trinitrobenzene, whereas 6 per cent, of sulphur 
would be required. Further, in the latter case, the unavoidable 
presence of free, uncombined sulphur lowers the technical value 
of many rubber wares. The use of different organic compounds 
for vulcanization of caoutchouc allows of considerable variation 
in the physical properties, e. g., flexibility, elasticity, etc., besides 
in the color, smell, etc. Vulcanization may be effected by mono-, 
di- and tri-nitrobenzenes, -toluenes, etc., tri- and tetra-nitronaph- 
thylamines picramic acid, picryl chloride, artificial musk, nitro- 
cyclohexane, nitro-dyestuffs, etc. Metallic oxides, which facili- 
tate the vulcanization of rubber by sulphur and enhance the value 
of the product obtained, exert a similar effect on vulcanization by 
nitro-derivatives. Lead oxide is most valuable in this respect, 
and then follow, in order, oxides of zinc, calcium, magnesium, 
barium. On the other hand, mixtures of aliphatic amines with 
the above oxides, although they accelerate vulcanization by sul- 
phur or lower the temperature of the process by 10 to 15 degrees 
C, retard vulcanization by nitro-compounds and lower the value 
of the corresponding product. Like sulphur and sulphur chlor- 
ide, nitro-derivatives vulcanize, not only caoutchouc, but also 
various vegetable oils yielding products analogous to factice. 

The vulcanization of caoutchouc by means of peroxides pro- 
ceeds considerably more rapidly and at a lower temperature than 
vulcanization by means of sulphur or even nitro-compounds. 



8 It might be expected on theoretical grounds that caoutchouc would 
be vulcanized under suitable conditions by oxides of nitrogen, hydrogen 
peroxide, ozone, ozonides of the terpenes, oxygen or air in presence of 
compounds which activate oxygen, and many other substances. 

9 From the "Journal of the Russian Physico-Chemical Society," 1915, 
pages 1,462-1,467. Abstract from "Journal of Society of Chemical In- 
dustry," Vol. XXXV, p. 59. 



BENZOYL PEROXIDE 283 

The theoretical significance of this process has been already con- 
sidered in earlier papers. 

Vulcanization by the action of benzoyl peroxide has been 
investigated in detail. It is found: (1) That metallic oxides 
which accelerate the vulcanization of caoutchouc by means of 
sulphur or nitro-compounds — PbO, ZnO, MgO, CaO, etc. — are 
almost without effect on vulcanization by benzoyl peroxide; in 
some cases they diminish the velocity of the process, and in most 
instances increase the oxidizability ; that is, the rate of decompo- 
sition, of the given vulcanizate. (2) Colophony and other resins 
lower the stability of caoutchouc on vulcanization by benzoyl 
peroxide. (3) Mixtures of amines and metallic oxides, which 
were found by the author to act as accelerants of the ordinary 
vulcanization of caoutchoucs by sulphur, retard vulcanization 
by the new method and decrease the stability of the correspond- 
ing vulcanizate. (4) Proteins exert a similar influence on the 
vulcanization of caoutchoucs by means of sulphur, nitro-com- 
pounds or peroxides ; they increase the extensibility and the con- 
stant K', i.e., the tensile strength of the vulcanizate. 9 " 

On normal vulcanization by means of benzoyl peroxide the 
physical structure of caoutchouc is not destroyed. It is, how- 
ever, necessary to avoid excess of the peroxide and, for every 
given benzoyl peroxide mixture, to establish exactly the neces- 
sary temperature and time for the vulcanization. If not, the 
vulcanizate will exhibit, like "abnormal" and also like chemically 
pure caoutchoucs, negligible extensibility and tensile strength ; 10 
the protein compounds may be oxidized by the benzoyl peroxide, 
and their destruction may be accompanied by that of the physical 
structure of the given caoutchouc. 

Caoutchoucs normally vulcanized by benzoyl peroxide ex- 
hibit both qualitatively and quantitatively all the typical prop- 
erties of caoutchoucs vulcanized by either sulphur or nitro-com- 
pounds ; when kept, they do not change. 11 Caoutchoucs vulcan- 
ized with a slight excess of benzoyl peroxide soon (1-5 days) 



9ffl From the "Journal of the Russian Physico-Chemical Society," 1915, 
pages 1,467-1,471. Translated from the original Russian by T. H. Pope, 
B.Sc. 

10 Presumably corresponding with over-vulcanization in the case of 
ordinary rubber and sulphur compounds. — H. P. S. 

11 Samples of vulcanized caoutchouc have been kept for six months 
without change. 



284 VULCANIZATION WITHOUT SULPHUR 

develop on their surface soft, colorless, crystalline leaflets, which 
are as transparent as glass, and possess pronounced lustre ; after 
the lapse of a longer time (1, 3 or 5 months) the vulcanizate 
begins to oxidize and gradually becomes sticky; finally it runs, 
becoming converted into a sticky, more or less viscous, plastic 
mass. 12 The vulcanizate decomposes especially rapidly when in 
contact with the original, non-vulcanized mixture, which evi- 
dently acts as a "detonator." 

Consequently, when different mixtures of caoutchouc and 
benzoyl peroxide are either heated or stored, two processes take 
place simultaneously: (1) Vulcanization of the original caout- 
chouc, this being connected with partial or complete union of the 
oxygen of the peroxide with the caoutchouc, and (2) oxidation 
of the caoutchouc by the benzoyl peroxide with formation of 
the highly sticky mass mentioned above. 

The relative rates of these two processes determine the ef- 
fect of the vulcanization, and experiment shows that these rates 
depend on the proportion of benzoyl peroxide, on the tempera- 
ture, and on the prolongation of the vulcanization, and on the 
nature and quantities of the foreign matters in the initial mixture. 

Vulcanization of caoutchouc with benzoyl peroxide re- 
quires, therefore, increased attention or skill in the operator. 

When once started at a high temperature, the process of 
vulcanization continues comparatively rapid, even at the ordin- 
ary temperature. Thus, it was found that a mixture of normal 
erythrene caoutchouc and a small excess of benzoyl peroxide 
converted after 27 days into a very sticky, viscous mass, which 
later gradually runs or assumes the form of the containing ves- 
sel. When previously heated, without access of air, two minutes 
at 85 degrees C, the same mixture does not run when kept 
at the ordinary temperature; on the other hand, the stickiness 
already present disappears spontaneously; the plasticity of fresh 
sections and their proneness to become sticky are lost, and the 
mixture gradually vulcanizes at the ordinary temperature, and 
finally even over-vulcanizes, owing to the excess of benzoyl 
peroxide present. 



12 Some caoutchoucs, for instance, normal erythrene caoutchouc, vul- 
canized with a large amount of benzoyl peroxide, gradually solidify when 
kept, yielding a dense, brittle mass, easily powdered but absolutely with- 
out stickiness. 



OXIDATION AND VULCANIZATION 285 

It is seen that the relative velocity of oxidation, on the one 
hand, and of vulcanization on the other, depend on the charac- 
ter of the preliminary treatment, in the given case on the two 
minutes' heating at 85 degrees C. 

This fact explains immediately why incomplete vulcaniza- 
tion protects caoutchouc from oxidation or decomposition in the 
air. 

The benzoyl peroxide may be replaced by perbenzoic acid, 
and probably by ozone, ozonides of caoutchouc or terpenes, nitro- 
gen, oxides, certain metallic peroxides and hydrogen peroxide. 

Further, my observations show that barium peroxide pro- 
duces no trace of vulcanization in caoutchouc. Into natural Para 
caoutchouc were introduced 1 per cent., 5 per cent., 10 per cent., 
15 per cent, and 50 per cent. Ba0 2 , the mixtures being vulcanized 
for 5 minutes, 10 minutes, 30 minutes, and 2 hours with steam 
at 2, 3 and 4 atmospheres pressure in a press; under these con- 
ditions the mixture underwent no change, its plasticity and even 
its light color remaining quite unaltered. This interesting ob- 
servation lends further confirmation to the fact that vulcaniza- 
tion of caoutchouc by the above method takes place at the ex- 
pense, not of the peroxides themselves, but of their active oxy- 
gen. 

The accompanying table contains recipes for the vulcaniza- 
tion of different caoutchoucs with benzoyl peroxide. It must 
be pointed out, however, that the external conditions indicated 
in this table are by no means ideal. 13 

To conclude, in presence of 0.5-3 per cent, of benzoyl perox- 
ide, normal synthetic caoutchouc, obtained on coagulation of its 
solution, undergoes at about 80 to 120 degrees C. incomplete vul- 
canization. The external appearance, and all the new properties 
of the product obtained, compel the assumption that some forms 
of natural rubber represent products of incomplete (incipient) 
vulcanization caused by active oxygen. 14 

Very recently a United States patent [1,242,586] has been 
granted to Dr. Ostromislensky for a new process of vulcanization 
and the product resulting. The process is an interesting one, 
since it eliminates the time-honored use of sulphur for vulcani- 



13 The detailed recipes for the vulcanization of caoutchouc by means 
of benzoyl peroxide, together with other documents kept in my pocket- 
book, were unfortunately stolen from me. 

14 Or by compounds containing active oxygen, etc. 



286 VULCANIZATION WITHOUT SULPHUR 

zation and may possibly indicate a distinct advance in the devel- 
opment of the industry. 

To quote from the patent specification, the process is de- 
scribed essentially as follows : 

The invention consists in treating a mass of rubber with 
halogen or halogen-acid compounds of natural and synthetic 
rubber, such as rubber chlorides and hydrochlorides, chlorides 
and bromides of the synthetic rubbers. These substances may 
be prepared by the direct action of halogens or halogen acids 
on solutions of rubber. The halogen compound, chloride or 
bromide of rubber, is first reduced to a fine powder and then 
combined with the rubber on the mixing rolls. The proportions 
employed are 10 grams of rubber and 7 grams of 2.3 dimethyl- 
erythrene rubber bromide. The material is placed in the vul- 
canizing press and heated for one and a half hours at 130 de- 
grees C. The product is an ebonite-like mass. 

As alternative procedure, 10 grams of rubber, 85 grams of 
natural rubber bromide heated at 130 degrees C. for two hours, 
produced a similar ebonite-like material. Seven grams of rub- 
ber heated with 10 grams of cauprene bromide at 130 degrees 
C. for two hours gave a similar result. Three-tenths gram of 
rubber, heated with 3.6. grams of cauprene chloride at 130 de- 
grees C. for two hours and twenty minutes, gave an ebonite-like 
mass only superficially colored black. 

The substances thus obtained are similar in color to ordinary 
ebonites, and possess equal stability and physical properties. 
They do not conduct electricity, may be easily cut and polished 
and retain the luster even in damp air. 

Soft rubber may be produced by vulcanization with hydro- 
chlorides of natural rubber. The preferred proportions given 
are one part of natural rubber heated with \6y 2 parts of hydro- 
chloride of natural rubber at 130 degrees C. for two hours. The 
resulting soft rubber is generally applicable where soft rubbers 
produced by sulphur vulcanization have been used. 

A similar form of vulcanization takes place when unvulcan- 

ized rubber is subjected to the action of an ozonide of rubber. 

This ozonide may be prepared by subjecting layers of rubber 

from one-half to one millimeter in thickness to the action of a 

stream of dried air under the influence of the rays of a mercury 



VULCANIZING AGENTS 287 

lamp. After an increase in weight of the original rubber from 
two-tenths to one per cent, is secured, the product is milled on 
cold rollers and then reheated for one to 15 minutes at 100 to 
120 degrees C. If a small quantity of the ozonides are mixed 
with un vulcanized rubber and subjected to heat in the usual 
manner in a vulcanizing press, vulcanization is satisfactorily 
accomplished. According to the quantity of the ozonides added 
to the natural rubber, either soft or hard rubber may be produced. 

The process is applicable not only to natural rubber, but 
may be applied to various synthetic rubbers. For example, tests 
carried out with dimethylerythrene and normal erythrene pro- 
duced good results. 

A British patent [108,300] based on Ostromislensky's re- 
searches, has been granted in which vulcanization without the 
use of sulphur is accomplished by still other groups of agents 
and accelerators. Quoting from the specifications, the invention 
is applicable to natural or synthetic rubbers from isoprene, ery- 
threne, and dimethylerythrene. In an example, 50 grams of rub- 
ber are mixed with two grams of 1-3-5 trinitro-benzene, one 
gram of naphthylamine, and ten grams of lead oxide, and the 
mixture is vulcanized by heating for 55 minutes under a steam 
pressure of 45 pounds per square inch. The following examples 
of suitable vulcanizing agents are specified : 

Mono-, di-, and tri-nitrobenzols and toluols, tri- and tetra- 
nitronaphthalenes, picric and picramic acids, picryl chloride, arti- 
ficial musk, nitrocyclohexane, aurotin, and many other nitro dye- 
stuffs. Aniline, naphthylamine, pyridine, piperdine and di- 
isoamylamine are used as accelerators in the presence of metallic 
oxides; they also prevent aging. Amines may be replaced by 
traces (0.05 per cent.) of sulphur, antimony, or substances hav- 
ing an alkaline reaction — for example, sodium alcoholate. Oxides 
of lead, zinc, calcium, magnesium, and barium also act as accel- 
erators. The nitro-compounds and other substances may be 
employed under all the conditions under which sulphur is em- 
ployed for vulcanization. 



288 VULCANIZATION WITHOUT SULPHUR 



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CHAPTER XVII. 

RECLAIMED RUBBER AND ITS USES. 

The industry of reclaiming rubber from vulcanized waste- 
rubber articles developed from experimental beginnings as a 
necessary adjunct of the manufacture of rubber goods. Re- 
claimed rubber has risen in estimation and increased in import- 
ance, until its output has attained an annual tonnage equaling 
about half that of the world's total production of crude rub- 
ber for the same period. It is thus a very important division of 
the rubber industry and a marked economic factor in its develop- 
ment. The growth of the rubber-reclaiming trade naturally 
tends to eliminate the small factory reclaiming plant, because of 
the more effective economies and the better standardization of 
product possible under the conditions of operation that obtain 
with companies of large capital, world-wide connections and 
specialized effort. Such reclaiming companies employ special 
machinery, and maintain research and analytic laboratories for 
control of their processes, standardization of products and study 
of reclaiming and compounding problems. 

Reclaimed rubber, known also as regenerated and devulcan- 
ized rubber, can be compounded, manufactured and vulcanized 
after the manner of crude rubber. The better grades are avail- 
able as compounding material for quality as well as economy. 
The lower grades afford inexpensive and useful compounds for 
many mechanical goods, molded articles and proofed fabrics. 

The following figures will give a rough idea of the amount 
of reclaimed stock produced annually in the United States and 
the sources from which derived. 

Tons 
Reclaimed 
Sources Rubber 

Boots and shoes 40,000 

Automobile tires 40,000 

Mechanicals and sundries 10,000 

Inner tubes 4,000 

Solid truck tires 7,000 

Total United States production 101,000 

290 



WASTE RUBBER GRADES 291 

The vast and varied collections of vulcanized waste rubber 
are subject to sorting and classification into a number of more 
or less standard grades before shipment to the reclaimers, who 
continue the sorting for their own purposes. The official market 
specifications of waste rubber, standardized by The Rubber Re- 
claimers Division of The Rubber Association of America, in- 
clude 34 grades, classified as follows: 

Rubber boots and shoes, 5 grades; 

Auto tires, 8 grades; 

Solid tires, 2 grades; 

Hose, 4 grades; 

Inner tubes, 7 grades; 

White rubber, 3 grades; 

Wringer rolls, 2 grades; 

Red rubber, 3 grades; 

Mixed black rubber; 

Matting and packing. 

Reclaimed rubber, known also as recovered or regenerated 
rubber, shoddy, and crumb, is produced from worn-out rubber 
goods. There are two general methods in vogue, known respec- 
tively as the mechanical and the chemical processes. Where the 
mechanical process is followed, the waste is ground to a fine 
powder, which is run over magnets to extract the iron, and is 
then put through a blowing process, which separates the woolen 
or cotton fibers from the rubber. The rubber powder is then 
subjected to a high degree of heat (the process known as devul- 
canization), and afterwards sheeted, when it is similar to unvul- 
canized rubber compound. 

The chemical process is similar to the mechanical, except 
that the fiber is destroyed by means of acid or alkaline solutions 
and quite a percentage of it is washed out with the residue after 
the process is finished. Special grades of reclaimed rubber are 
made from mechanical goods that have high-grade frictions in 
them and also from unvulcanized scrap. Rubber is also reclaimed 
from ordinary mechanical goods such as hose, belting, and pack- 
ing, and for certain purposes is mixed with what is known as 
shoe shoddy. White scrap, from wringer rolls, tubing, druggists' 
sundries, pneumatic tire treads, and the like, is also produced. 
The great trouble with the white is that, on second vulcanization, 



292 RECLAIMED RUBBER 

it is apt to be very hard. At one time hard-rubber dust was to 
be found in the market and was used as a shoddy in certain 
grades of vulcanite. There is today but very little of it to be 
found, however, as most of the manufacturers of hard-rubber 
goods find a use for all that they make. 

The processes followed in the reclaiming of waste rubber 
are no longer secret. Those who are in the business of manu- 
facturing for the trade are able to do it, as a rule, because they 
buy waste stock at a lower figure than a small user could, be- 
sides which, by manufacturing the goods in larger quantities, 
they can do it more economically and maintain higher average 
grades than it could be done in a small way. 

In this business are used crackers, sheeting mills like ordi- 
nary grinders, and, indeed, general machinery not dissimilar to 
that used in a mill where crude rubber is compounded. They 
have in addition, however, lead-lined tanks for acid treatment,, 
vulcanizers or, better, devulcanizers, huge vats for washing, 
magnets for removing metal, sieves, and drying facilities. This 
branch of the rubber business is not supposed to be deeply in- 
terested in compounding, in spite of the fact that it is sometimes 
suggested that earthy matters, heavy adulterants, and oils do find 
a use in reclaiming mills. 

Rubber scrap of any sort vulcanized or unvulcanized, is 
actively sought for reclaiming the world over. The larger fac- 
tories use their own scrap of both kinds yet much unvulcanized 
scrap gets upon the market chiefly in the form of Para cable 
strippings, mackintosh cloth cuttings, frictioned fabric, and ce- 
ment ball. 

Next to this in value, and indeed often more valuable, is the 
pure gum vulcanized scrap, such as rubber thread, and a variety 
of floating stocks that do not contain rubber substitutes. Special 
high-grade stocks, such as inner tubes, billiard cushions, balloon 
fabrics, etc., are favorites in this line. 

Automobile tires constitute the largest single item in scrap 
collection. Ten years ago old rubber boots and shoes occupied 
this position, and now rank second. Old rubber boots and shoes 
are graded roughly by the country of their origin — American, 
English, German, Russian and so on — and their conversion into 



PROCESSES 293 

workable rubber has long been the backbone of the reclaiming 
business. 

Most of the products of the mechanical goods factory come 
into the market as waste eventually, and are sorted and graded 
according to the richness of the compound, and the freedom from 
metal and fabric. In this line is the red scrap, such as valves ; the 
drab, embracing wringer rolls, mattings, buffers and hose, graded 
as air brake, fire-hose linings and garden hose. Then there is 
the grading of belting, asbestos scrap, red and other packing. 

In tires there is the collection and sorting of solid tires into 
cab, baby carriage and truck tires. In pneumatics, there are 
single and double tube bicycle tires, motor-cycle casing and auto- 
mobile tire shoes — American, French, and German. There is 
also the inner tube in gray, red, and black that is today a large 
factor in the recovery business. 

In druggists' sundries, water bottles and the like furnish 
white and red rubber, while air and water beds, sponges and 
many other specialties furnish regular grades. 

In hard rubber, cells, telephone receivers, sheets and rods 
are ground up and used again, while hard-rubber shavings and 
dust find a ready market. 

Gutta-percha, in the form of cable strippings, balls and 
buckets, is a type of waste with a recognized place. 

And these are but a few of the many grades put out by the 
sorters, and sold to the scores of reclaiming plants the world 
over, that produce tons of usable rubber from what was once 
thrown away or burned under the factory boilers. 

Almost the first attempt at recovering rubber waste was that 
done at the Beverly Rubber Works, in Massachusetts, back in 
the fifties, when Hiram L. Hall boiled waste vulcanized rubber 
in water, after reducing it to a powder, and then sheeted it. It is 
a curious fact that, in one little mill to-day, the manufacturer 
grinds his own scrap, boils it in hot water until it is in condition 
to sheet, and makes a fair article out of it. 

The year after Hall's patent, another was granted to Francis 
Baschnagel, who paved the way for devulcanization by covering 
a process whereby a finely ground rubber was exposed to the 
action of live steam. It was not, however, until E. H. Clapp 
took hold of the business and discovered a process for blowing 



294 RECLAIMED RUBBER 

the fiber out of the finely ground rubber prior to its devulcaniza- 
tion that the goods began to be used to a large extent. 

The next step in the progress of the art was characterized by 
the taking out of a great variety of patents, most of which depend 
upon various acids and alkalies for destroying the fiber. These 
patents were more than fifty in number, and were fully reviewed 
with their attendant processes in the famous suits brought by the 
Chemical Rubber Co. against The Goodyear's Metallic Rubber 
Shoe Co. and the Raymond Rubber Co. While it would be 
tedious to go into that matter, it is interesting to touch upon im- 
portant processes involved. The action of acids upon fibers, of 
course, had long been known ; in connection with the rubber busi- 
ness, however, it was without doubt novel. The Hayward patent, 
for instance, mixed 75 pounds of sulphuric acid with 8 hogs- 
heads of water, and in this way the fiber was weakened so that 
it was easily ground up with the rubber. The Faure patent called 
simply for the immersion of the clippings in an acid, which in 
disintegrating the textile matter set the india rubber free. Hiram 
Hall advised the use of lime or alum to eat up the cloth, and also 
a solution of 1 part of sulphuric acid to 9 parts of water. Burg- 
hardt used muriatic acid for destroying the cloth fiber. The 
Heinzerling patent called for a treatment first with acids, and 
then with alkalies. It is also to be remembered that Charles 
Goodyear directed that crude india rubber should be subjected 
to a 10 per cent, solution of sulphuric acid to eat up the bark 
with which the gum might be contaminated. 

The Mitchell patents, the Bourn patents, and others, where 
an extremely dilute acid was used, and where a concentrated 
acid was called for, have been so thoroughly reviewed that those 
familiar with the rubber business know all about the processes 
employed. 

What is known as the alkali process, based upon the patents 
of Arthur Hudson Marks, is one of the notable improvements in 
reclaimed rubber in more recent years. Factories for reclaiming 
under this process are operated in the United States, England, 
Germany and Belgium, mechanical waste being chiefly used. 

In addition to the processes in more general use, a few 
unusual ones may be interesting. For example, the Torstrick 
process, in which dilute nitric acid and fusel oil were mixed with 



PROCESSES 295 

the gum in a heated state, or passed through it in the shape of 
vapors, making the mass sticky, after which a small quantity of 
chloride of calcium was added and the gum sheeted. 

Conrad Poppenhusen mixed rubber scrap with essential oils, 
a little turpentine being used preferably, left the scrap until it had 
become soft, and then passed dry gaseous ammonia into the mass, 
forming a gelatinous viscid product. 

C. F. E. Simond mixed 2 parts of chloride of lime with 100 
parts of waste rubber, and brought it to a high degree of heat, 
by which the sulphur was volatilized, which took from 15 to 60 
minutes, and then used the rubber over. 

Thomas J. Mayall mixed vegetable tar with waste rubber — 
exposed it to the heat of the sun, or to a gentle artificial heat, and 
got a soft pasty mass that he was able to work with crude rubber. 
He also invented a process for sprinkling the finely ground rub- 
ber with camphene and setting the mass afire in a partially 
covered vessel, his claim being that if the fire was stopped at a 
certain point, a tough viscid mass was the result, which contained 
neither sulphur nor fiber, and could be reworked like unvulcan- 
ized rubber. 

Beylikgy exposed vulcanized rubber for a number of days to 
a temperature of 250 degrees F., after which he claimed that it 
became an adhesive mass, insoluble in alcohol, partially soluble 
in ether, and wholly soluble in benzol. He called this caout- 
choucite and claimed that it could be vulcanized with the addition 
of sulphur at a lower temperature than ordinary crude rubber. 

McCartney, of Glasgow, mixed vulcanized rubber with 
naphtha and a little acetic acid. He also added camphor, and by 
the action of heat produced in reality a rubber paint. 

The following are briefs of some of the later claims of in- 
ventors in rubber vulcanizing: 

Anderson's process (English). Ground scrap is mixed with 
calcium sulphide and coal-tar naphtha, exposed to heat, and 
thoroughly washed. 

Alexander's process relates to the production of india rubber 
latex from rubber waste. The waste is heated under pressure in 
benzine. The dissolved matter is then removed, and the solution 
is heated again in sodium hydrate. The benzine is distilled off 
and the aqueous solution of caoutchouc filtered and precipitated 
with acid. 



296 RECLAIMED RUBBER 

Basle process. A Swiss process which covers the use of 
various ethers boiling at a temperature of about 100 degrees C. 

Brimmer's process (German) consists of mixing ground 
scrap with castor oil, heating until dissolved, adding alcohol for 
precipitation and washing with a weak solution of caustic soda. 

Clift's process (English). Waste rubber is dissolved in a 
base of the pyridin group, treated with acid in the presence of a 
volatile solvent for the separation of the rubber from the base, 
then the solvent separated, leaving with the rubber in solution. 

The Chautard process (French) uses commercial phenol for 
reclaiming, the phenol being later distilled off. The whole proc- 
ess is quite intricate. 

The Durvez process (Belgian). Rubber waste boiled with 
water and finely powdered lime. Product is washed, rolled, and 
dried. 

Eves's process (American). Devulcanizing by treating with 
sodium sulphate in the presence of heat, then incorporating 
barium chloride. 

French process. Waste vulcanized rubber is heated with 
terpin hydrate, the mixture is then treated with boiling water, 
and from the residue the regenerated caoutchouc is extracted by 
means of a suitable solvent, such as commercial xylol. The terpin 
hydrate is recovered for use over again by cooling the hot aque- 
ous wash-liquors. 

French process. The finely divided rubber is heated, pref- 
erably at 110 degrees to 180 degrees C, under pressure, with a 
soap solution, to which may be added other substances, such as 
aliphatic or aromatic hydrocarbons, oil of turpentine or the like, 
and salts capable of forming solutions which dissolve sulphur, 
such as alkali sulphides, alkali sulphites, etc. 

Gilbert-Besaw process (American). This process is not 
patented, but is secret. It is applicable to the recovery of any 
sort of rubber scrap, whether cured in open steam, in molds, or 
in dry heat. According to the statement of the inventors, no acid 
or alkali, or anything that can be in any way injurious, is added. 
The machinery for treating *the waste rubber for the removal of 
fiber and for devulcanization is individual to the process. The 
time occupied in devulcanization is about one-quarter that used 



PROCESSES 297 

in existing processes. No residuum or oily matter of any sort 
is added to the product, either before or after de vulcanization. 

Gregory and Thorn's process (English). Reclaimed in the 
usual way; then a solvent is added which is a mixture of aniline 
oil and naphtha. The product is heated in open steam until the 
solution of rubber is complete, when it is taken out and strained. 

Gubbin's process (English). Unvulcanized scrap in which 
the fabric is saturated with naphtha and passed through plain 
pressure rolls to remove the rubber from the fabric. 

Heinzerling's process (German). Ground waste rubber 
treated with aniline or its homologs at 140 degrees to 180 de- 
grees C. The rubber is then mechanically separated from the 
residue; is treated with dilute sulphuric acid, and the separating 
rubber is washed and dried. 

Heyl-Dia's process. Heats ground rubber under moderate 
pressure in naphtha, temperature being not more than 120 de- 
grees F. The naphtha is then drawn off and with it most of the 
sulphur. The rubber is then heated to over 350 degrees F., with 
a fresh solvent when it dissolves. The solvent is then removed 
and the sulphur washed and dried. 

Hyatt and Penn's process. Waste rubber finely ground, is 
put into a vacuum chamber and molded into goods under heat. 

Karavodine's process (French) consists of pulverizing the 
material, adding asbestos fibers which have been previously 
treated with a binding medium, and subjecting the mass to a 
higher pressure at higher temperature. 

Kessler's process. Waste rubber is treated with carbolic 
acid in a vacuum. After solution powdered acetate of lead is 
added and the whole submitted to distillation. Caustic soda is 
used later for neutralizing. 

Kittel's compound (Austrian). Powdered waste mixed 
with caustic alkalies is compressed into cakes and heated 2 or 3 
hours at 280 degrees C. 

Koneman's process (American). Ground waste is boiled 
in a salted-acid solution, and a mixable fixed hydrocarbon is then 
added. 

Koener's process (German). Waste rubber is heated with 
solvents, such as benzine, for a time, after which the solution is 
further heated with water and solvent subsequently distilled off. 



298 RECLAIMED RUBBER 

Marks's process (American). Waste rubber finely ground 
is heated in a dilute alkaline solution in a closed vessel for a 
time and at a temperature dependent upon the amount of sul- 
phur present. 

Murphy's process (American) uses for devulcanizing a 
bath consisting of carbonate of soda and gallic acid. 

Neilson's process (German). The inventor uses resin oil 
as a solvent, filters and precipitates the rubber by means of a 
ketone. 

Passmore's process dissolves vulcanized waste with eucalyp- 
tol and removes mineral matter by filtrating. The eucalyptol is 
driven off by having steam forced through the mass. 

Penther's process (German). A devulcanizing machine of 
German origin makes what is known as American reclaimed rub- 
ber. It separates the fiber from the rubber so thoroughly that 
the fluff is a merchantable product in the felt trade. 

Peterson's process (American) consists in subjecting 
shredded waste to an alkaline solution raised to a boiling tem- 
perature under hydraulic pressure, next washing in water solu- 
tion containing phenol under a high temperature and pressure. 

Price's process (American) uses caustic solutions of marked 
strength, under ordinary atmospheric pressure. 

Price's process (English). A process whereby waste rubber 
cut into pieces of suitable size is roughly mixed with crude rub- 
ber and ground flint, and without being vulcanized, by great 
pressure molded into finished goods. 

Roux process (French). The inventor describes a machine 
which devulcanizes powdered waste rubber and makes it into 
tubing at the same time. In other words it is a combination of 
a devulcanizer and tubing machine. 

Steenstrup's process. The waste is heated in a solution of 
alkali and hydrofluoric acid under steam. The product is then 
washed, dried, etc. 

Theilgaard's process (Denmark). The inventor has several 
patents which cover the treatment of vulcanized scrap by alka- 
line earths and such solvents as sodium sulphide. 

Wheeler's process (American) consists in subjecting the 
waste particles individually to a current of heated fluid moving 
through a confined passage. 



PROCESSES 299 

Zuhl's process (English). Vulcanized waste is dissolved in 
five times its weight of naphthalene at a low temperature. The 
naphthalene is then distilled from the mixture with steam. 

Actual restoration of the rubber content of vulcanized rub- 
ber to its original unvulcanized state has not been accomplished 
by any of the preceding methods. The alkali processes of re- 
claiming remove the free sulphur, but the product contains all 
the combined sulphur originally united with the crude rubber. 
The nature of the problem is purely chemical and the subject 
of active research. 

One of the latest and chemically successful processes is that 
of Dr. David Spence, from whose patent specifications are 
quoted the following observations on the chemical nature of the 
important problem of rubber-reclaiming methods. 

The removal of free sulphur from vulcanized rubber can 
readily be effected and, in conjunction with a certain plasticising 
or depolymerizing action on the rubber, analogous to the plasti- 
cising action of mechanical working and heat on raw rubber, the 
removal of free sulphur is all that is effected by present-day 
processes of rubber regeneration. An interesting process de- 
scribed by Spence has for its object the removal of not merely 
traces of the combined sulphur, but of large proportions of the 
combined sulphur of vulcanization, and is applicable not merely 
to rubber waste containing 2 to 3 per cent, of combined sulphur, 
but to the product of complete saturation of the rubber hydro- 
carbon, known as hard rubber (which contains as its principal 
constituent a body considered to have the formula C 10 H 16 S 2 ), 
which may contain as much as 32 per cent, of combined sulphur. 
The process is in line with the fact that the vulcanization of 
rubber by sulphur is a reaction whose velocity can be accelerated, 
and to be technically successful, therefore, requires an acceler- 
ator to facilitate the reaction. The more powerful the acceler- 
ator employed, the more violent and the more complete will be 
the reaction. Without such an accelerator the vulcanization of 
rubber proceeds very slowly, even at high temperatures, where- 
as in the presence of even a trace (1/100 of 1 per cent.) of a 
suitable accelerator, vulcanization of rubber by sulphur can be 
effected in a few minutes. By reason of the character of the 
vulcanization process it appeared to Spence, therefore, that the 



300 RECLAIMED RUBBER 

true solution of the problem of effecting a real devulcanization 
of vulcanized rubber must lie in the use of a powerful vulcaniz- 
ing accelerator in conjunction with an element capable of com- 
bining with and fixing the sulphur liberated from the rubber by 
the accelerator. The more powerful the accelerator, the more 
marked should be the results obtained by the means of it, and 
this principle should govern the choice of the accelerator em- 
ployed. Theoretically, all that is necessary is a powerful accel- 
erator and an element of substance to combine with the sulphur 
set free by the accelerator. The presence of this latter substance 
even will be unnecessary if the accelerator itself is employed in 
excess and is capable of forming a stable derivative with the sul- 
phur under the temperature and other conditions of the experi- 
ment. The principle has been tested by experiments, and it has 
been found to form the basis of a successful desulphurization of 
vulcanized rubber, Spence having succeeded in effecting the re- 
moval of large proportions of the combined sulphur from vul- 
canized india rubber by the use of several of the most powerful 
of those reagents, which are known as "catalysts," or more 
usually "accelerators," employed in vulcanization. A solution of 
aniline-potassium or of aniline-sodium in excess of aniline which 
is formed by the action of dry aniline on metallic potassium, or 
sodium can be used very effectively in removing combined sul- 
phur from vulcanized rubber; this solution in addition to its 
accelerant action actually serves as a means of fixing the sul- 
phur liberated from the rubber as an insoluble metallic sulphide. 
As an example of a powerful organic accelerator, which is very 
effective in removing combined sulphur, piperidine may be men- 
tioned. Caustic soda — long since shown to be one of the most 
powerful of inorganic catalysts — is another suitable substance 
for effecting removal of combined sulphur of vulcanized india 
rubber. This substance has the advantage of being cheap. 

Generally speaking, Spence has found that it is best to work 
with all components of the reaction in solution ; and in this con- 
nection the use of a solution of aniline-potassium in excess of 
aniline sufficient to dissolve the rubber at the operating tempera- 
ture is particularly advantageous. In this case, the rubber, as 
well as the accelerator, is brought into intimate contact in ani- 
line solution, and the sulphur which is liberated is thrown out 



PROCESSES 301 

of the field of reaction as an insoluble alkaline sulphide. In the 
case where caustic soda is employed as the devulcanizing agent, 
the less complete devulcanization effected is explained by the 
fact that no solvent or means has yet been found of bringing 
this accelerator and the rubber together in homogeneous solu- 
tion. Vigorous agitation facilitates the reaction. Similarly, the 
process, in order to effect the best results, should be carried out 
in absence of moisture, the presence of water having been found 
to be particularly disadvantageous. The temperature at which 
the reaction may be carried out may vary within wide limits 
according to the reagents used; the higher the temperature, 
within certain limits, the better will be the results obtained, and 
for practical purposes it is found that a temperature of about 
170 to 180 degrees C. is usually advantageous. 

As examples of the effectiveness of his process, Spence cites 
examples of the reduction of the combined sulphur from 78 to 
90 per cent, in one operation in soft vulcanized rubber and 73 
per cent, in hard rubber. 



CHAPTER XVIII. 

PHYSICAL TESTS AND ANALYSES OF CRUDE AND 

VULCANIZED RUBBER. SPECIFIC GRAVITY. 

SPECIFICATIONS FOR TESTING RUBBER 

GOODS. 

It long has been the boast of expert rubber superintendents 
and manufacturers that they find little trouble in matching com- 
pounds. As a matter of fact, some of them are remarkably 
expert. Given a small sample of vulcanized rubber in a familiar 
line and the price at which it must be produced, they are often 
able, without much experimenting, by their knowledge of rub- 
ber and compounding ingredients, to get a result apparently 
similar. 

This, in fact, was the only way possible when rubber manu- 
facturers operated on individual knowledge and experience and 
in self-defense conducted their processes secretly and without 
scientific assistance. Under modern conditions it is no longer 
advisable, even for experienced superintendents, to attempt close 
duplication of particular rubber compositions or to meet speci- 
fied requirements by inspection for odor, color, weight or quali- 
tative hand tests of strength, stretch and hardness. 

Rubber manufacturers are no longer credited by important 
customers with exact knowledge of what will best serve the 
needs of the latter; hence specific specifications, the laboratory, 
the development department, and the introduction of team-work 
in the coordination of science and practical experience on the 
part of chemist, superintendent, and heads of factory departments. 

To meet these conditions, the rubber manufacturer requires 
intimate knowledge concerning the origin and preparation of 
market grades of crude rubber and methods for determining 
their quality. 

Standardization of regular factory product, including con- 
siderations of quality as well as price, calls for application of 
the scientific method. 

302 



VALUATION OF CRUDE RUBBER 303 

The production of goods for the army and navy, fire de- 
partments and railroads, insulation for power, light and tele- 
phone companies and other public or semi-public service cannot 
be conducted without laboratory facilities in charge of a scien- 
tific staff. 

The function of a rubber-work's laboratory briefly outlined 
includes : ( 1 ) systematic examination of the chemical and physi- 
cal characteristics of crude rubbers, compounding ingredients, 
and accessory materials, such as fabrics and metals used in rub- 
ber goods; (2) standardization of materials, compounds, vul- 
canization and other processes and manufacture of goods to 
specification; and (3) control of factory processes. 

The rubber work's laboratory is usually equipped in close 
adjustment to the needs of factory control; it therefore varies 
somewhat, due to the nature of the factory production. In addi- 
tion to facilities for analytic work it generally includes testing 
apparatus of general or special adaptability for mechanical and 
electrical testing. A selection of laboratory-size machinery is 
very desirable for manufacturing operations on an experiment- 
ing scale, such as washing, drying, mixing, calendering, and vul- 
canizing. The best equipped works' laboratories are essentially 
rubber factories in miniature, in which complete studies can be 
made of materials and processes without interference with fac- 
tory routine or production. 

It is unnecessary to mention here the equipment of chemi- 
cals and apparatus needed in a laboratory for chemical analysis. 
Such information is easily accessible in the chemical and appa- 
ratus catalogs of laboratory supply houses. The following 
chemical methods are given in detail because they are standard 
and issued by the Government and by important official and 
trade associations. 

VALUATION TESTS OF CRUDE RUBBER. 

Scientific and rule-of -thumb valuing of plantation rubber 
have recently been compared for the Dutch Rubber Congress. 3 

The investigation included 137 specimens, 36 samples of 
sheet, all but one of which was smoked, and 101 samples of 
crepe, six of which were thick blankets. These were all judged 



1 J. G. Fol, "Mededeelingen van dem Rijksvoorlichtingsdienst ten 
behoeve van den Rubberhandel en de Rubbernijverheid te Delft." 



304 ANALYSES OF RUBBER 

in an empiric way by the producers and their conclusions re- 
served and compared after completion of the scientific tests made 
without knowledge of the first results. 

AN ABSTRACT OF THE SCIENTIFIC METHOD AND FOl/s CONCLUSIONS. 

Empiric judging of rubber depends largely on color, smell, 
and stretch. These tests at best are only roughly approximate, 
although the rubber expert by means of them can distinguish 
marked differences in quality. It is a mistake to presuppose that 
mechanical properties of the rubber when vulcanized run parallel 
to color, smell and stretch in the raw state. Variations in physi- 
cal condition do not permit hand-pulled tests nor quantitative 
expression of value. The influence of temperature variations is 
also marked. 

Smoked sheet cannot be judged better by rule of thumb than 
crepe. Its color denotes only the degree of smoking. Sheet is 
easier judged as to its mechanical properties than crepe. 

Black rubber presents the most difficulties for empiric judg- 
ment, as it cannot be subjected to a hand test. 

Scientific methods obviate these objections, because each 
sample is suitably prepared and tested quantitatively. The 137 
samples under investigation were examined after the following 
scheme : 

A. Chemical Analysis : 

1. Moisture. 

2. Resin. 

3. Ash. 

4. Nitrogen calculated as albumen. 

5. Rubber. 

6. Acetic degree. 

B. Viscosity Number. 

C. Vulcanization and Physical Tests : 

1. Tensile strength. 

2. Elongation. 

3. Permanent set after 24 hours at 400 per cent. 

stretch measured after six hours' rest. 

4. Temporary set measured directly after release from 

400 per cent, stretch. 

5. Determination of load necessary to stretch sample 

400 per cent, (kilograms per square centi- 
meter) . 



CHEMICAL AND PHYSICAL PROPERTIES 305 

C. Vulcanization and Physical Tests (Continued) : 

6. Difference of the load necessary to stretch sample 

400 per cent, and that required for the last- of 
five successive 400 per cent, stretchings. 

7. Elasticity or rebound. 

8. Coefficient of vulcanization. 

Concerning the importance and correlation of these deter- 
minations, Fol concludes: (1) chemical analysis is not sufficient 
alone for judgment of the rubber quality. Properties of rubber 
are chiefly determined by the physical nature of rubber and the 
rubber molecule. The quantitative chemical differences are not 
enough to account for the large differences found in the physical 
properties; (2) in general a high viscosity indicates good me- 
chanical properties of the rubber after vulcanization. However, 
the opposite must be assumed with some reservation, since in 
studying the relation between the viscosity and tensile strength it 
appeared that various samples with a low viscosity had a very 
high tensile strength. The samples that exhibited this relation 
were almost exclusively smoked sheet. This phenomenon is 
caused by the fact that it is very difficult to dissolve smoked sheet 
in benzol completely. The dissolved part has a low viscosity 
and presumably contributes little to the excellent qualities shown 
by the sample after vulcanization, while the very considerable 
amount of undissolved rubber apparently is the most valuable 
part of the sample and most probably causes the good properties 
after vulcanization. 

The tensile strength permanent set after stretching 400 
per cent, and the coefficient of vulcanization were taken as 
quantities suitable for classifying the samples. These quan- 
tities are closely related. Thus, high tensile strength generally 
accompanies high coefficient of vulcanization and low permanent 
set. Elongation at break also indicates the quality of the rub- 
ber; of samples equally loaded, that is the best which has the 
highest elongation at break. 

The remainder of the physical tests made were set aside as 
practically valueless for the end in view. 

One of the most important points demonstrated by this in- 
vestigation is the lack of uniformity in first latex rubber. The 
greatest divergencies were found in viscosity, tensile strength, 



306 ANALYSES OF RUBBER 

permanent set and the coefficient of vulcanization. The causes 
of this lack of uniformity and its prevention are among the most 
important problems of the rubber industry. 

The rubbers investigated were classified as follows : 

Breaking strain Coefficient of 

Class (kilograms per sq. c. m.) Permanent set. vulcanization. 

I 135 k. g. and over Maximum 5% Minimum 5 

II 120k.g.to 135 k.g. 5% to 7% Minimum 4 

III 90 k. g. to 120 kg. 7% to 12% Minimum 3 

IV 80 k. g. to 90 k. g. Over 12% Below 3 

V Below 80 k. g. Over 12% Below 3 

The division of the 137 samples among the different classes 
is indicated below: 

' Class Sheet Crepe Blanket. 

1 17 2 3 

II 12 21 3 

III 7 51 2 

IV 11 1 

V 9 

Totals 36 95 6 

These figures demonstrate clearly that, in general, smoked 
sheet is better than crepe. However, there are samples of crepe 
that are equal to smoked sheet as far as mechanical properties 
are concerned. The number of samples of blanket is too small 
to permit a decisive conclusion, but the figures would indicate 
that blanket is inferior in quality to smoked sheet and often 
also to crepe. 

Lack of uniformity in plantation rubber reveals itself 
chiefly in the difference in rapidity of vulcanization. Two rub- 
bers outwardly of absolutely equal value may produce entirely 
different results after vulcanization. Empiric judgment cannot 
tell how a rubber will behave during vulcanization, hence the 
estimate of value is liable to be incorrect. This causes much 
uncertainty and disappointment to the manufacturer. 

The researches of K. Gorter on the viscosity index as a 
standard for the preliminary testing of crude rubber are ab- 
stracted as follows: 3 

The viscosity index is the logarithm of the viscosity of a 
1 per cent, solution and is superior as a standard to the viscos- 

2 One sample unsmoked. 

3 "Chemical Abstracts," October 10, 1916. 



EXAMINATION OF CRUDE RUBBER 307 

ity, being less dependent on the temperature than the latter, 1 
degree causing a variation in the viscosity index of only 0.005. 
Hence it is not necessary in viscosity determinations to keep the 
temperature constant by means of a thermostat. The viscosity 
index multiplied by the factor 70 gives the tensile strength of 
the rubber sample. Gorter's viscosimeter consists of a pipette 
with a 10 cm. capillary stem with an opening 1.42 mm. in 
diameter, the whole fitting into a 150 cc. Erlenmeyer. The in- 
dicated capacity of the pipette is 15 cc, and its constant 9.8 at 
26 degrees C. One gram of rubber is dissolved in 120 cc. ben- 
zene (not purified from thiophene) with shaking, using a brown 
flask. The solution is filtered after 24 hours and the concen- 
tration determined, after which the viscosity is determined by 
the pipette. The relative viscosity of a rubber solution equals 
the period of delivery, divided by the constant of the viscosi- 
meter for the solvent used. The viscosity of a rubber solution 
is dependent on the dimensions of the viscosimeter used; hence 
to obtain comparable results the same instrument must invari- 
ably be used. 

Below is outlined Schidrowitz's method for the examination 
of crude rubber. 4 

The examination of crude rubber may involve: 

(a) Chemical analysis, with a view to determining the 
quantity of pure rubber and of various impurities, and, to a 
certain extent, in some instances, the nature of the latter. 

(b) Physical or mechanical tests, carried out either on the 
crude material or on the latter modified by the vulcanizing proc- 
ess, with a view to determining the physical and mechanical 
qualities of the rubber substance. 

Chemical analysis has hitherto been subordinate in the 
commercial evaluation of rubber, partly on account of lack of 
exact knowledge regarding the nature of the secondary products 
(resins, nitrogenous substances, etc.), and partly owing to the 
absence of specific information on the influence exercised by 
them on the vulcanization process on the one hand, and on the 
more important attributes (strength, elasticity, etc.), on the 
other hand. 



4 Philip Schidrowitz, Ph.D., the "Analyst," May, 1915— "Recent Ad- 
vances in the Analyses and Evaluation of Rubber and Rubber Goods." 



308 ANALYSES OF RUBBER 

If the difficulties associated with the chemical investigation 
of the nature and influence of the "impurities" necessarily make 
progress in this direction slow, it is not surprising that the work 
having as its object the identification and evaluation by chemical 
means of different rubber substances or caoutchoucs is still in 
a more or less embryonic state. 

Recent work by Caspar! suggests the possibility of dis- 
criminating, up to a point, by physico-chemical methods, be- 
tween caoutchoucs of different commercial quality. According 
to> Caspari, rubber is of a composite character and consists of 
(1) "soluble" rubber, which is a weak but elastic colloid, sol- 
uble in light petroleum, and (2) of "insoluble" or "pectous" 
rubber, which is an elastic colloid of considerable mechanical 
strength. The latter, in some respects resembling a slightly vul- 
canized material, preserves its structure on contact with sol- 
vents. It is, however, gradually dissolved by benzene and car- 
bon tetrachloride, but whereas the viscosities of the soluble in 
Brazilian and plantation Para, respectively, are very similar, 
the "pectous" in the latter is far more readily attacked by ben- 
zene or carbon tetrachloride than the "pectous" of the former. 
According to Caspari, Brazilian fine contains 35 to 50 per cent, 
of "pectous," whereas plantation rubber examined by him 
showed no more than 10 to 25 per cent. Caspari believes that 
"nerve" or strength is mainly due to the "pectous" variety. The 
work of Caspari will require confirmation and amplification 
before it is applied to rubber evaluation. It suggests a new 
field of research, indicating the possibility of estimating the qual- 
ity by a direct physico-chemical method. 

Secondary Products — Rubber Resins — The outstanding 
feature of the work of Heinrichsen and Marcusson is that all 
resins, excepting that from Para {Hevea), are optically active. 
In certain cases, therefore, the absence of optical activity in the 
extracted resin may be taken as evidence that no rubber other 
than Hevea is present. Para resin contains 15 per cent, and 
other resins up to 100 per cent, of unsaponifiable matter. The 
optical activity appears to be mainly due to the latter. Iodine 
values varying from 30.6 for jelutong resin to 118 for Para 
resin were found. So far as the investigation has been carried 



METHODS OF TEST 309 

it appears that the resins from vulcanized rubber exhibit the 
same characteristics as those from the crude material. D. Bloom, 
as the result of the examination of 150 samples of resin from 
different species, concluded that the "acid value" of the resin 
from the same species is constant. 

The effect of rubber resin on vulcanizing capacity is a mat- 
ter of controversy. Litharge has been shown to be practically 
inoperative as a catalyst in the absence of rubber resins. Where 
litharge or other catalyst was not employed it has been found 
that the rubber resins do not exercise any marked effect on the 
curing capacity. 

Mechanical Impurities. — Beadle and Stevens give the fol- 
lowing method (for these materials only). They "depolymer- 
ize" the rubber by heating with a solvent of high boiling point, 
thinning still further with a solvent of low viscosity, filtering 
and weighing. 

Insoluble Matter — Nitrogenous Substances. — This item 
does not apply to accidental mechanical impurities, but to natu- 
ral and normal substances always present to some extent in crude 
rubber. While there is no proof that normal "insoluble" is 
essentially a nitrogen product (a part doubtless consisting of 
oxidation products) it is fairly certain that it normally contains 
a high proportion of nitrogen. 

Schmitz's method, 2.5 grams rubber, treated with 50 c.c. 
pentachlorethane for five to seven hours at 85 to 90 degrees C. 
with the formation of very fluid solution readily filterable, par- 
ticularly if somewhat diluted with chloroform. The residue can 
be further purified by dissolving in five per cent, solution of 
sodium hydroxide and reprecipitating with hydrochloric acid. 

Practical Considerations. — There is considerable evi- 
dence to warrant the assumption that the "insoluble" matter in 
crude rubber has an important bearing on vulcanizing capacity, 
but no quantitative relation has been discovered. While it has 
been shown that the removal of the "insoluble" markedly de- 
creases curing capacity, the experience of the author is that rub- 
bers with low proportions of "insoluble" do not necessarily cure 
badly, nor do samples with high "insoluble" necessarily cure 



310 ANALYSES OF RUBBER 

rapidly. Probably "insoluble" varies so in composition that 
further methods of separation must be devised before "insol- 
uble" can be taken as a criterion of quality. The author prefers 
the indirect method for determining "insoluble," which consists 
in evaporating a convenient volume of clear solution, obtained 
by treating 0.5 to one gram of rubber with 100 to 200 c.c. ben- 
zene in a tall cylinder, allowing to settle and weighing the residue 
in a pipetted portion drawn off from above the residue. 

Estimation of Rubber. — Assuming a satisfactory method 
of separating the "insoluble" matter, the most satisfactory indi- 
rect method of estimating rubber is by deducting the sum of 
moisture plus resin plus "insoluble" from 100. This method in- 
volves the assumption that the whole of the ash and nitrogen is 
present in insoluble form. The author recommends the return 
of the analysis in the following form: 

Moisture Per cent. 

Resin (acetone extract) 

Insoluble matter 

Rubber (difference) 

The above contains: 

Ash (mineral matter) 

Nitrogen 

Nitrogen = protein 

These notes apply only to routine technical analysis of which 
the chief object is to ascertain whether a distinct abnormality is 
disclosed and to control methods of production or of gauging 
suitability for specific manufacturing purposes. 

Direct Method by Tetrabromide for Determining Rub- 
ber. — The reader is referred for details of this method to the 
work by Caspari on "Laboratory Methods for Rubber Analysis." 

The reaction of bromine on caoutchouc is C 10 H 16 4- 6 Br = 
C 10 H 14 Br 4 + 2 H Br. 

Estimation of Moisture. — The best method is (1) to dry- 
in water oven at 98 degrees C. till an increase in weight becomes 
apparent or for a standard time of two hours, or (2) to take 
the difference between original weight of sample and weight 
after acetone extract plus the extract. 



PHYSICAL AND MECHANICAL TESTS 311 

Washing Loss. — It is generally agreed that if the sample is 
large and requires washing the analytical determination should 
be carried out on the washed, air-dried material. 

PHYSICAL AND MECHANICAL TESTS. 

Viscosity. — A low viscosity almost invariably indicates 
poor quality. A determination of swelling capacity (per Cas- 
pari) may give more satisfactory results. 

Adhesive Test. — Beadle and Stevens determine the load re- 
quired to separate pieces of paper evenly coated with a solution 
of rubber. The paper is coated by drawing it over the surface 
of a five per cent, (or less) solution. 

Mechanical Tests. — By this is meant tensile tests. These 
are of no value as applied to raw rubber. 

Vulcanization Tests. — (a) Material. State of aggrega- 
tion (degree of polymerization) or physical condition of the 
rubber substance, quality and nature of resin, and of "insoluble" 
matter and acidity. 

(b) Process. Temperature, duration of cure, method of 
heating, quantity of sulphur; and if fillers are used, their nature 
and quantity. So long as our knowledge of the physical and 
chemical nature of the impurities and of the rubber substances 
is incomplete it is impossible to devise any method of analysis 
or physical test which will enable us to determine quantitatively 
the effect of the various factors on vulcanization. Direct vul- 
canization tests are, therefore, for the present, essential for the 
purpose of practical evaluation. Broadly stated such may com- 
prise : (a) observations on material during or rather towards the 
process; (b) observations on the nature of the vulcanized prod- 
uct, with regard to "rate of cure," relying on the mechanical 
properties of the cured stock. 

There appears to be no direct connection between the "co- 
efficient of vulcanization" and the technical properties of the 
material. Various types of tensile tests have been devised and 
are applied to vulcanized rubber. There is an essential differ- 
ence between tests for the comparative evaluation of crude rub- 
ber and tests applied with the view of examining the specific 
properties of any given rubber article. With regard to the 
former it is desirable to use methods calculated to measure cer- 



312 ANALYSES OF RUBBER 

tain intrinsic and typical properties of the raw material, such as 
curing capacity, strength, distensibility and capacity for recov- 
ering. 

Any system of evaluation based on factors influencing the 
vulcanization process must be carried out under standardized 
conditions of mixture, cure and test. Pure rubber and sulphur 
are considered the best, because most uniform and also because 
a filler renders the reaction less delicate. 

THE ANALYSIS OF VULCANIZED RUBBER. 

The pioneer work of rubber analysis was done by Dr. 
Robert Henriques and Dr. Carl Otto Weber. Following these 
distinguished chemists others have worked on the problems and 
as a result there is available an excellent selection of reliable 
analytic methods. Standard methods have been adopted for 
specification purposes by the United States Bureau of Stan- 
dards, Washington, District of Columbia; American Society for 
Testing Materials, Philadelphia, Pennsylvania; National Board 
of Fire Underwriters' Laboratories, Chicago, Illinois ; Joint 
Rubber Insulation Committee, American Institute of Electrical 
Engineers. 

A complete analysis of vulcanized rubber includes : 

1. Acetone extract: (a) free sulphur, (b) waxes. 

2. Chloroform extract, mineral rubber, tar or asphalt. 

3. Alcoholic potash extract, rubber substitutes. 

4. Total sulphur. 

5. Ash and mineral analysis. 

6. Rubber. 

7. Specific gravity. 

REMARKS ON ANALYSIS. 

The following remarks in explanation of the analysis are 
from Circular 38 on "Testing of Rubber Goods," by the United 
States Bureau of Standards. 

Acetone Extract. — Acetone extracts the rubber resins, 
the free sulphur, and any mineral oils or waxes that may have 
been used. The difference in amount between the total acetone 
extract and the free sulphur present indicates something re- 
garding the quality of the rubber present. For the best grades 



METHODS OF TEST 313 

of Para rubber this should not exceed five per cent, of the rub- 
ber. The presence of mineral oil indicates the possibility of 
reclaimed rubber having been used. 

Free Sulphur. — The free sulphur is that part of the sul- 
phur originally added as such which remains unchanged after 
vulcanization. Small amounts of free sulphur are not harm- 
ful and it is difficult to place a limit beyond which it is to be 
considered excessive. A limit is usually placed on the free sul- 
phur in high-grade insulation compounds, chiefly because it may 
corrode the copper wire. 

Total Sulphur. — Sulphur occurs in vulcanized rubber as 
free sulphur, in combination with the rubber, and at times in 
the mineral fillers, reclaimed rubber, and rubber substitutes. 
It is limited in specification in high-grade material in order to 
eliminate undesirable sulphur minerals and prevent as far as 
possible the use of inferior or reclaimed rubbers and rubber 
substitutes. The inferior rubbers require a larger percentage of 
sulphur than Para for proper vulcanization, while reclaimed 
rubber and substitutes contain usually large amounts of sulphur. 
Ash and Sulphur in the Ash. — The ash or residue after 
ignition, consists principally of the non-volatile mineral fillers. 
It is used in calculation of the rubber by difference. The sul- 
phur in the ash is determined merely for the purpose of obtain- 
ing a correction figure and has no other significance. 

Barytes. — There is no objection to the sulphur presence 
in mineral fillers, provided the mineral containing it has no 
injurious effect on the rubber, and that amount of such sul- 
phur may be readily determined. Barytes is such a substance 
and is permitted in practically all compounds where the amount 
of sulphur is limited by specifications. There are no other fill- 
ers which as yet fulfil both of the conditions named. 

Rubber. — The determination of the amount of rubber 
present in a vulcanized compound is both important and dif- 
ficult. The procedure extensively used is to calculate the per- 
centage of rubber by the difference between 100 per cent, and 
the sum of the ash (sulphur free), total sulphur, and corrected 
acetone extract. It is as good as any method yet devised, al- 
though not always accurate. 



314 ANALYSES OF RUBBER 

Specific Gravity. — It is apparent that with equal per- 
centages by weight of ingredients, a compound of a given spe- 
cific gravity will have less rubber per unit volume than one of 
higher specific gravity. In order to insure a minimum volume 
of rubber, specific gravity limits are stated. 

Chloroform Extract. — The so-called mineral rubbers, 
such as tar, bituminous substances, elaterite, gilsonite, etc., are 
used extensively as rubber substitutes. These substances are 
partly soluble in acetone, but the material so removed is not 
characteristic of these substitutes and not readily distinguished 
from vaseline and similar mineral oils. Part of the insoluble 
portion remaining after the treatment with acetone is soluble 
in chloroform, the solution being very dark in color. Properly 
vulcanized high-grade rubbers yield only a small amount dur- 
ing the chloroform extraction, the solution being practically 
colorless. 

Alcoholic-Potash Extract. — Some rubber substitutes are 
prepared by the action of sulphur or sulphur chloride on vege- 
table oils. Alcoholic-potash extraction detects the presence of 
such substitutes and gives some idea of the amount. Para rub- 
ber contains only a small percentage of material extracted by 
this solvent. 

BUREAU OF STANDARDS' METHODS OF ANALYSIS. 
preparation of samples. 

(1) Soft Rubber — A sample of not less than 25 grams 
shall be prepared by taking pieces from various parts of the 
original sample. With those having cover and tube, separate 
samples of each shall be made. From fire hose remove the back- 
ing before grinding. 

(2) Grinding. — The sample shall be cut into small pieces 
and then run through a grinder, taking for analysis only such 
material as will pass a 20-mesh sieve. Care must be taken to 
see that the grinder does not become appreciably warm during 
the grinding. If the nature of the material is such that it gums 
together so that it will not pass through the sieve (as would be 
the case with under- vulcanized samples), it will be sufficient to 
pass the material through the grinder twice and accept all the 
material for the finer sample. 



ANALYSES OF MECHANICAL GOODS 315 

(3) Hard Rubber. — Samples of this material shall be 
prepared for analysis by rasping. 

(4) Reagents. — All reagents shall be of the chemically 
pure quality, specially tested before use. 

(5) Acetone shall be freshly distilled over anhydrous 
potassium carbonate, using the fraction obtained at 56 degrees 
to 57 degrees C. 

(6) Alcoholic Potash. — Shall be of normal strength, 
made by dissolving the required amount of potassium hydroxide 
in absolute alcohol and allowing it to settle. Only the clear solu- 
tion shall be used. 

(7) The Nitric Acid-bromine Reagent shall be pre- 
pared by adding a considerable excess of bromine to concen- 
trated nitric acid, shaking thoroughly, and allowing it to stand 
for some hours before using. 

(8) The Fusion Mixture for sulphur determinations 
shall be made by mixing equal quantities of sodium carbonate 
and powdered potassium-nitrate. 

(9) Barium-chloride Solution shall be made by dis- 
solving 100 grams of barium chloride in one liter of distilled 
water and adding two or three drops of concentrated hydro- 
chloric acid. If there is any insoluble matter of cloudiness, the 
solution shall be heated on the steam bath overnight and filtered 
through 589 Schleicher and Schull blue-ribbon filter paper. 

ANALYSIS OF MECHANICAL GOODS. 

(10) Acetone Extract. — Place a 2-gram sample in an 
acetone-extracted Schleicher and Schull paper thimble and ex- 
tract continuously with acetone for eight hours, unless the solu- 
tion in the thimble is still colored at the end of that time, when 
the extraction shall proceed the next day for a further period of 
four hours. Transfer the extract to a tared 100 or 150 c.c. 
Erlenmeyer flask, using chloroform or benzene for dissolving 
any material which may have been separated from the solvent 
during the course of the extraction. Drive off the solvents at as 
low a temperature as possible, using a gentle current of air. Dry 
the flask and contents in an air bath at 90 degrees to 95 degrees 



316 ANALYSES OF RUBBER 

C. ; cool and weigh. Call the residue "acetone extract, uncor- 
rected." Calculate the results to percentage. 

(11) Free Sulphur. — Add to the flask (paragraph 10) 
containing the acetone extract, uncorrected, 50 to 60 c.c. of dis- 
tilled water and two or three c.c. of bromine. (If the acetone 
extract indicates a large amount of free sulphur, the amount of 
bromine used may be increased.) Heat gently on the steam bath 
until the solution is practically colorless, and filter into a 250-c.c. 
beaker. Cover the beaker with a watch glass, heat to boiling on 
the steam bath, add 10 c.c. of 10 per cent, barium chloride solu- 
tion, and allow the precipitate to stand overnight. The next day 
filter the precipitate on an 11 cm. 590 Schleicher and Schull filter 
paper. Ignite in a small porcelain crucible, using a small Bunsen 
flame and not allowing the paper to inflame; cool and weigh. 
Calculate the barium sulphate to sulphur by means of the factor 
0.1374, and calculate the percentage of free sulphur. 

(12) Total Sulphur. — Place 0.5 grams of rubber in a 
porcelain crucible of about 100 c.c. capacity. Add 20 c.c. of the 
nitric acid-bromine mixture (paragraph 7), cover the crucible 
with a watch glass, and allow to stand for one hour. Heat very 
carefully for an hour, remove the cover, rinsing it with a little 
distilled water, and evaporate to dryness. Add five grams of 
fusion mixture (paragraph 8) and three to four c.c. of distilled 
water. Digest for a few minutes, and then spread the mixture 
half way up the side of the crucible to facilitate drying. Dry on 
a steam bath or hot plate. Fuse the mixture, using a sulphur- 
free flame, until all the organic matter has been destroyed and 
the melt is quite soft. Allow to cool, place the crucible in a 600- 
c.c. beaker, and cover with distilled water. Digest three or four 
hours on the steam bath. Filter into a 800-c.c. beaker, washing 
thoroughly with hot water. The total volume should be about 
500 c.c. Add seven to eight c.c. concentrated hydrochloric acid 
to the filtrate, and heat on the steam bath. Test the solution 
for acidity with congo paper, add 10 c.c. of 10 per cent, barium 
chloride solution, and allow to stand overnight. Filter barium 
sulphate as before. Calculate to percentage of sulphur present. 

(13) Ash. — Wrap a 1-gram sample in an 11 -cm. 590 
Schleicher and Schull filter paper, and after extracting with ace- 



BUREAU OF STANDARDS' METHODS 317 

tone for four hours transfer to a medium-sized porcelain cruci- 
ble and ignite at the lowest possible temperature; cool and 
weigh. 

(14) Sulphur of Ash. — Add a few drops of concentrated 
nitric acid to the ash (paragraph 13), stir with a small glass 
rod and evaporate off the excess acid on the steam bath. Add 
five grams of fusion mixture (paragraph 8) and heat until fused. 
When cool, place the crucible in a 400-c.c. beaker, cover with 
water, and heat on the steam bath for two or three hours. Filter 
into a 600-c.c. beaker (reserve the insoluble residue for testing 
according to paragraph 15), add seven to eight c.c. concentrated 
hydrochloric acid to the filtrate, cover, and heat to boiling on the 
steam bath. Add 10 c.c. of 10 per cent, barium chloride solution, 
and allow to stand overnight. Treat the barium sulphate pre- 
cipitate as under paragraph 11. Calculate the sulphur by the 
factor 0.1374. 

(15) Barytes. — In case the total sulphur is limited by 
specification and barytes is permitted as a filler, the latter must 
be determined, since the sulphur present in this mineral must 
be deducted from the total sulphur. The barytes is calculated 
from the barium in the ash, determined as follows: filter off the 
insoluble matter after the fusion and extraction in paragraph 
14, wash back into the original beaker with hot water, add five 
c.c. of 10 per cent, hydrochloric acid, and heat the solution on 
the steam bath until as much as possible is dissolved. Filter 
through the same filter, as before, washing thoroughly with hot 
water. Nearly neutralize the solution with sodium carbonate, 
leaving it slightly acid. Saturate the solution with hydrogen sul- 
phide, and when the lead sulphide has settled filter into a 
400-c.c. beaker and wash thoroughly. The total volume should 
not be over 200 c.c. Cover the beaker containing the filtrate, 
heat to boiling, and add 10 c.c. of 10 per cent, sulphuric acid. 
Allow the precipitate to stand overnight. Filter off the barium 
sulphate as directed in paragraph 11. Calculate the percentage 
of barytes. Then calculate the percentage of sulphur in the 
barytes by the factor 0.1374. 

(16) Calculations. — (a) Subtract the free sulphur 
from the "acetone extract uncorrected," and report the differ- 



318 ANALYSES OF RUBBER 

ence as "acetone extract corrected." (b) Subtract the sulphur 
in the ash from the ash as determined in paragraph 13, and 
report "ash, sulphur-free." (c) Subtract from the total sul- 
phur determined according to paragraph 12, the percentage of 
sulphur present as barytes, if the latter determination has been 
made (see paragraph 15), and report the difference as "total 
sulphur corrected." Then add the sulphur so deducted to the 
ash, in this case reporting the latter simply as "ash corrected." 
In other words, only the sulphur other than that in barytes will 
be deducted from the ash when the total sulphur is corrected 
for barytes. (d) Subtract from 100 per cent, the sum of the 
"acetone extract corrected," total sulphur (corrected or not, as 
the case may be), and ash (sulphur-free, or corrected for sul- 
phur other than barytes), and call the remainder "rubber by 
difference." (e) Divide the "acetone extract corrected" by 
the sum of the "acetone extract corrected" and the "rubber by 
difference" and call the result "ratio, acetone extract to rubber." 
It will be simpler to express the results in percentages. When 
new rubber only is used this will give the percentage of ace- 
tone-soluble matter in the rubber. 

(17) Specific Gravity. — Make this determination in a 
pycnometer, using about 5 grams of rubber cut into small strips, 
taking care to avoid having air bubbles adhering to the rubber. 
Do not use a ground sample for this determination, since it is 
intended to determine the specific gravity of the compound as 
a whole. Aside from the difficulty of completely removing air 
bubbles, the specific gravity of a sample which is at all porous 
will be, after grinding, higher than when this is determined on 
strips. Calculate the specific gravity on the basis of water at 15 
degrees C as 1.00. 

(18) Alcoholic-potash Extract. — Fire hose, tested 
according to the National Board of Fire Underwriters' specifi- 
cations, calls for an alcoholic-potash extraction. It is performed 
on the dried rubber remaining after the acetone extraction. 
Complete method appears in paragraph 28. 

ANALYSIS OF 30 PER CENT. PARA INSULATION. 

(19) General. — The determinations to be made on high- 
grade insulation compounds are acetone extract, unsaponifiable 



ANALYSIS OF INSULATION 319 

matter, waxy hydrocarbons, free sulphur, ash, and total sulphur, 
and sometimes alcoholic-potash and chloroform extracts. 

(20) Acetone Extract. — Determine as under para- 
graph 10. 

(21) Unsaponifiable Matter. — Add to the acetone ex- 
tract (paragraph 20) 50 c.c. normal alcoholic potash (para- 
graph 6), heat on steam bath under a reflux condenser for two 
hours; remove the condenser and evaporate to dryness. Trans- 
fer to a separatory funnel, using about 100 c.c. water; add 25 
c.c. ether, and shake. Allow the two layers to separate thor- 
oughly, then draw off the water layer. Continue the extraction 
of the water layer with fresh portions of ether until the ether 
will no longer remove any unsaponifiable matter; unite the 
ethereal layers, and Wash with distilled water, adding the first 
wash water to the extracted aqueous layer. This aqueous solu- 
tion is reserved for the free sulphur determination (paragraph 
23). Transfer the ether to a tared Erlenmeyer flask, distil off 
the ether, dry at 90 degrees to 95 degrees C. ; cool and weigh. 

(22) Waxy Hydrocarbons. — To the unsaponifiable matter 
(paragraph 21) add 50 c.c. absolute alcohol and heat on the 
steam bath for one-half hour. Place the flask in a mixture of 
ice and salt and let stand for one hour. Filter off the separated 
waxy hydrocarbons, using Schleicher and Schull 589 blue-ribbon 
filter paper, and applying a gentle suction. Wash with alcohol 
which has been cooled in an ice-salt mixture. The funnel should 
be surrounded by a freezing mixture in order that the tempera- 
ture may not rise during filtration. Dissolve the precipitate from 
the filter paper with hot chloroform, catching the solution in a 
weighed 100 to 150-c.c. beaker. Wash the flask with hot chloro- 
form and add the washings to the same beaker, in order to in- 
clude any insoluble matter adhering to the walls of the flask. 
Evaporate off the solvent, dry the residue at 90 degrees to 95 
degrees C, cool and weigh. 

(23) Free Sulphur. — Transfer the aqueous solution 
(paragraph 21 ) to a 250-c.c. beaker, and heat on the steam bath 
until the ether has been removed. Add 25 c.c. bromine water, 
heat one hour, add five c.c. concentrated hydrochloric acid, and 



320 ANALYSES OF RUBBER 

heat until the excess of bromine has been driven off. (Test for 
acidity with congo paper; the amount of acid specified is suffi- 
cient if instructions are followed exactly, and a large excess of 
acid is to be avoided.) Filter into a 250-c.c. beaker, add 10 c.c. 
10 per cent, barium chloride solution and finish the determina- 
tion as under paragraph 11. 

(24) Ash. — Proceed as under paragraphs 13 and 14. 

(25) Total Sulphur. — Proceed as under paragraph 12. 
There will be no correction for barytes. 

(26) Calculations. — (a) Subtract the sum of the "free 
sulphur" and "waxy hydrocarbons" from the "acetone extract 
uncorrected," and report the difference as "acetone extract 
corrected." (b) Subtract from 100 per cent, the sum of the 
"acetone extract corrected," "waxy hydrocarbons," "ash sul- 
phur-free," and "total sulphur" and report the results as "rub- 
ber by difference." (c) Divide the "acetone extract corrected" 
by the sum of the "acetone extract corrected" and the "rubber 
by difference" and report the results under "ratio, acetone ex- 
tract to rubber," as under paragraph 16 (e). 

(27) Chloroform Extract. — Without removing the ad- 
hering acetone from the rubber (paragraph 20) extract with 
chloroform for four hours. Evaporate off the solvent in a 
weighed flask or beaker, dry at 90 degrees to 95 degrees C, 
cool and weigh. Reserve the rubber for the alcoholic-potash 
determination. 

(28) Alcoholic-potash Extract. — Dry the rubber 
(paragraphs 10, 18, and 27) at about 50 degrees to 60 degrees 
C, transfer to a 200-c.c. Erlenmeyer flask, add 50 c.c. alcoholic- 
potash solution, and heat under a reflux condenser for four 
hours. Filter through a folded filter into a 250-c.c. beaker, 
washing with 50 c.c. of 95 per cent, alcohol, and then 50 c.c. 
of boiling water. Evaporate the filtrate to dryness. Transfer 
the residue to a separatory funnel, using about 75 c.c. of dis- 
tilled water. Add a few drops of methyl orange, and acidify 
the solution with 10 per cent, hydrochloric acid. Extract with 
four portions of ether, 25 c.c. each, unless the fourth portion 
should be colored, when the extraction should be continued 
until no further quantity can be extracted. Unite the other 



CALCULATION OF RESULTS 321 

fractions, wash thoroughly with distilled water, and evaporate 
the ether in a weighed beaker. Dry at 90 degrees to 95 degrees 
C, cool and weigh. 

The methods of rubber analysis specified by The Ameri- 
can Society for Testing Materials, the National Board of Fire 
Underwriters' Laboratories, and the Joint Rubber Insulation 
Committee in general closely resemble those recommended by 
the United States Bureau of Standards. The Cottle extracting 
apparatus is specified in place of the all-glass apparatus of the 
Bureau of Standards. 

JOINT RUBBER INSULATION COMMITTEE'S 
METHODS. 

The percentage of rubber shall be considered to be the dif- 
ference between 100 and the sum of the total sulphur and ash 
expressed as percentages and figured on the total compound. 
If the alcoholic-potash extract is over two per cent, of the rub- 
ber as first calculated, subtract this excess also from the rubber. 
The organic-acetone extract shall be obtained by taking the dif- 
ference between the total acetone extract and the free sulphur. 
The organic acetone extract, free sulphur, total sulphur and 
alcoholic-potash extract shall be figured on the amount of gum 
as found by the above procedure. 

A general outline of the procedure is given on following 
page. It will be seen that the residues from the alcoholic-potash 
saponification are treated with hydrochloric acid to remove or- 
ganic matter, and the part insoluble in acid is dried and divided 
into two parts, one of which is used for the determination of 
sulphur, and the other ignited. A sulphur determination is also 
made on the ash. The rubber hydrocarbons as a percentage of 
the total sample are given by the following formula: 

C r E-F H "I 

Rubber Hydrocarbons = 100 — j 1 

4 L D G J 

The total weight of sample used in the determination is four 
grams and the letters C, D, E, F, G, and H represent the weights 
in grams of the substance in the diagram. 



322 



ANALYSES OF RUBBER 




MINERAL FILLERS IN RUBBER 323 

ANILINE METHOD FOR DETERMINATION OF MINERAL 
FILLERS IN RUBBER. 5 

Although the use of aniline as a solvent for vulcanized 
rubber is not new, there is very little information to be found 
concerning it in the literature. The following method is of 
much interest: 

In making the determination it is essential that the sample 
be finely powdered (20 mesh). A one-gram sample is extracted 
with acetone for four hours, dried at a low temperature, and 
then -transferred to a weighed 100 c.c. centrifuge tube. It is 
covered with 50 c.c. of pure aniline and 5 c.c. of nitrobenzene, 
stirred, covered, and heated at 160 degrees C, with occasional 
stirring until solution is complete. 

It is our practice to heat the samples overnight in a Freas 
oven, and in most cases the samples are completely dissolved 
by the next day. Sometimes the sample dissolves in three to 
four hours. If the rubber is not yet in solution, it can be seen 
by stirring with a glass rod. When solution is complete, there 
is nothing to be seen but fine pigment, free from rubbery ap- 
pearance. 

The chemist who makes the analysis for the first time may 
be uncertain of himself at this point, but after one or two deter- 
minations have been made he will at once recognize any undis- 
solved rubber. 

The tube is allowed to cool sufficiently, filled up with ether 
and well stirred. It is then centrifuged for 15 minutes at 1,500 
R.P.M. 

The supernatant liquid is decanted, about 25 c.c. of ether 
added and the pigment stirred up completely. It is centrifuged 
again and the decantate added to the first. Four washings with 
ether are sufficient. The tube is dried at 100 degrees C, cooled 
and weighed. The united decantates are evaporated and then 
ignited in a weighed porcelain or silica dish. The weight of 
fillers in it is added to that in the tube. 

The percentage of fillers plus that of total acetone extract 
is subtracted from 100 per cent., and the difference recorded in 
rubber gum. 



5 Otto H. Klein, John H. Link, and Frank Gottsch— "Aniline Method 
for Determination of Mineral Fillers in Rubber." American Chemical 
Society Proceedings, September, 1916. 



324 ANALYSES OF RUBBER 

Aniline differs from other solvents in that rubber dissolved 
in it forms a thin solution which permits the mineral fillers to 
separate readily. 

The small amount of nitrobenzene is used, because it makes 
solution more rapid. Semi-cured compounds dissolve more 
slowly than thoroughly cured soft stocks or very hard ones. 
With under-cured compounds, a soft, pasty mass is formed, 
which is very slow to dissolve, while this does not occur if the 
material is properly vulcanized. 

In some few cases an additional digestion with half the 
quantity of solvent for five hours will reduce the amount of min- 
eral fillers about 0.5 per cent. In specification work it is advis- 
able to make this second digestion after the ether has been ex- 
pelled from the tube by heating. 

Analysis of the fillers shows that the rubber as found by 
difference will not include the sulphur of vulcanization. 

The sum of the percentages of rubber found and organic 
acetone extract is slightly greater than the percentage of rub- 
ber used in the recipe. 

The fillers during vulcanization and afterwards in the 
course of analysis have combined with sulphur to form new 
compounds. If this combination of fillers and sulphur is a sub- 
stitution of sulphur for some other acid radical, the resultant 
product would weigh less than the sum of the ingredients enter- 
ing the reaction and the rubber found by difference would be 
slightly greater thereby. 

DIRECT DETERMINATION OF RUBBER BY 
WET COMBUSTION. 6 

The rubber nitrosite for combustion is prepared as follows: 
— After the rubber sample has been ground in a meat-chopper 
to pass a 20-mesh sieve, and a j4 gram of it extracted 3 hours 
with acetone, and Yz hour or longer with chloroform, the ex- 
tracted sample is allowed to dissolve in, or thoroughly absorb, 
chloroform. A small Florence flask (75 c.c.) is used, which 
may be about one-half full of the solvent. Nitrous oxide 
vapors, evolved from dilute nitric acid (specific gravity 1.3) 



6 L. G. Wesson and E. S. Knorr. "Wet Combustion in the Nitrosite- 
Combustion Method for the Direct Determination of Rubber." Ameri- 
can Chemical Society Proceedings, September, 1916. 



RUBBER BY WET COMBUSTION 325 

and arsenic trioxide, are then passed through the cooled chloro- 
form until the deep-green color becomes permanent for, say 15 
minutes, and the whole allowed to stand overnight for comple- 
tion of the action. 

The chloroform is then decanted through a dry Gooch 
crucible and asbestos matte (the former rests in an ordinary 
60-degree filter funnel) into the combustion flask, from which 
the chloroform is then evaporated by means of a boiling-water 
bath and a dry-air current. 7 

Meanwhile the residue in the Florence flask has been 
similarly dried. The separation of fillers and nitrosite is now 
brought about in the following way: Small portions (5 c.c.) 
of calcium chloride-dried ethyl acetate are added to the resi- 
due in the Florence flask, the latter warmed, and the liquid 
decanted through the Gooch crucible into the combustion flask, 
repeatedly, until the filtrate runs through entirely colorless. 
After evaporation of the acetate (recovery of the solvent as 
well) the residue is carefully freed from solvent by warming 
the containing flask in a boiling water bath for, say, 15 minutes, 
after which 15 c.c. of water containing 1 drop concentrated 
HC1, are added, and quickly evaporated by the use of a boiling 
calcium chloride bath and brisk current of dry air. The heat- 
ing is continued at least one-half hour after the residue is again 
apparently dry. 

The combustion apparatus consists of a 200 c.c. round- 
bottomed distilling flask, which is provided with a dropping 
funnel (100 c.c.) through a one-holed rubber stopper, and a 
series of U-tubes containing in order: (1) concentrated 
H 2 S0 4 — K 2 Cr 2 7 , renewed every 1 or 2 combustions; (2) 
water containing a drop of the preceding; (3) granular zinc; 
(4) calcium chloride; (5) soda-lime (weighed); (6) soda-lime 
and calcium chloride (weighed). 

The combustion is conducted as follows: The weighed 
soda-lime tubes in position, and the combustion flask cooled by 
water, a volume (20 c.c.) of cooled concentrated sulphuric acid 
is run rapidly into the flask on the nitrosite; then the cooled 



7 J. B. Tuttle, of the Bureau of Standards, has found that the chloro- 
form-soluble residue thus recovered may be very appreciable, and it is to 
his suggestion that this modification is due. 



326 ANALYSES OF RUBBER 

oxidizing solution of 10 grams pulverized K 2 Cr 2 7 in 75 c.c. 
concentrated H,S0 4 ,in a very slow stream. The flask may now 
be gently warmed by a sand bath to obtain a moderately rapid 
evolution of gas. 8 

This is done as long as gas continues to be evolved (about 
one hour), when a carbon dioxide free current of air, the heat- 
ing being maintained, is passed via the dropping funnel through 
the apparatus for at least one-half hour to sweep all carbon 
dioxide into the soda-lime tubes. 

136 

Weight C0 2 X X 200 gives percentage C 10 H 16 in the sample. 

440 

We hope, in conclusion, that further study and improve- 
ments of this method will eventually give a reliable and not 
too difficult procedure for the direct determination of rubber, 
not only in good quality compounds, but also in factice and 
other inferior substitute-containing rubbers. 

SULPHIDE SULPHUR. 

The presence of metallic sulphides and sulphates in tech- 
nical rubber articles complicates the estimation of the "com- 
bined" sulphur. Ordinarily the free sulphur and that present 
as substitute are extracted with acetone and alcoholic potash, 
respectively. In the absence of sulphides and sulphates an esti- 
mation of sulphur in the residue gives the percentage in com- 
bination with the rubber. In the presence of sulphides and sul- 
phates it is usual to heat a portion of the residue with high boil- 
ing point solvents to destroy the rubber and render it soluble. 
The sulphur is then estimated in the washed mineral residue. 
The sulphur is also estimated in another portion of the extracted 
rubber, and the sulphur combined with the rubber estimated by 
difference. 

The method is unsatisfactory and has two disadvantages. 
First, many vulcanized rubbers are decomposed with difficulty. 
They carbonize and cake even at carefully regulated tempera- 
tures. Consequently the residue, after washing with benzene, 



8 That carbon monoxide is formed during the combustion can be 
shown by allowing the gases which have passed the absorption train to 
come in contact with heated copper oxide and then barium hydroxide 
solution. A precipitate ensues, but the amount is not* appreciable for the 
results of the analysis. 



ESTIMATION OF SULPHIDE SULPHUR 327 

contains undissolved organic matter which protects the decom- 
position of the mineral sulphides. Second, the method assumes 
that the vulcanized rubber does not react with basic substances, 
such as litharge or magnesia, present in the mixing during heat- 
ing, with formation of metallic sulphides, although vulcanizing 
temperatures are employed. 

The method described below is due to H. P. Stevens and is 
applicable to those sulphides decomposable by heating with acids. 
It is, therefore, suitable for the estimation of the sulphides of 
zinc and lead. The metallic sulphides in either vulcanized or un- 
vulcanized rubbers are so protected by the rubber surrounding 
the mineral particles that the surface only is attacked by pro- 
longed boiling with strong hydrochloric acid solution. If the 
vulcanized rubber be first swollen in a suitable solvent in which 
the aqueous acid is partly soluble, the metallic sulphides of lead 
and zinc are easily and completely decomposed. Ordinary 
methylated ether has been found the most suitable solvent. If 
preferred, benzene or one of the chlorinated hydrocarbons, such 
as dichlorethylene, can be employed. Liberated hydrogen sul- 
phide is estimated and calculated to percentage of sulphide 
sulphur. 

Estimation of hydrogen sulphide by oxidation to sulphuric 
acid does not prove satisfactory. Best results are obtained by 
precipitation in lead acetate solution. The absorption is very 
complete in the first bottle. The freshly precipitated and 
washed sulphide is decomposed by shaking with iodine solution. 

ESTIMATION OF SULPHIDE SULPHUR. 

To determine the sulphide sulphur, 20 c.c. of concentrated 
hydrochloric acid and 30 c.c. of ether are placed in a Voigt's 
flask (a flask having a ground-in stopper carrying an outlet tube 
and a side-inlet tube which passes through the side of the flask 
and reaches nearly to the bottom). The air is expelled from 
the flask by a current of carbon dioxide. The flask is then con- 
nected with an absorption apparatus containing lead acetate 
solution and a weighed quantity of rubber is introduced. The 
rubber swells gradually and after about IS minutes the ether, 
together with evolved hydrogen sulphide, is driven over into the 
absorption apparatus by gentle heat. The decomposition is com- 



328 ANALYSES OF RUBBER 

pleted by boiling the mixture a few minutes. Traces of hydro- 
gen sulphide are removed by a current of carbon dioxide and 
the lead sulphide is collected, washed and titrated iodo- 
metrically. 

SULPHATE SULPHUR. 

The residue in the Voigt flask, containing the sulphates is 
extracted repeatedly with hydrochloric acid and the sulphates 
determined as barium sulphate. 

SOLVENTS FOR VULCANIZED RUBBER ANALYSIS. 

Ether, in presence of hydrochloric acid, gradually dissolves 
vulcanized rubber at the ordinary temperature, and the dissolved 
rubber contains about 1.5 per cent, of sulphur. A mixture of 
benzene and hydrochloric acid also dissolves vulcanized rubber. 
Chlorohydrocarbons act similarly to the mixture of solvents and 
hydrochloric acids, but are no more rapid than a mixture of ben- 
zene and acids. 

Douglas F. Twiss, in analytic work on rubber, finds that a 
mixture of equal parts by volume of concentrated hydrochloric 
acid and ether acts readily on rubber mixings at ordinary tem- 
perature, the penetration of the acid being facilitated by the 
swelling action of the ether. 

Another application for this reagent is the neutralization 
of accelerators, such as litharge, before attempting the removal 
of free sulphur from rapid-curing mixings. Where necessary 
to examine the contents of combined sulphur in a partially cured 
rubber-mix which contains much mineral accelerator and free 
sulphur, the conversion of the accelerator into an inert sub- 
stance before the acetone extraction has the advantage of 
removing the likelihood of vulcanization during extraction. 

To effect such purpose the procedure used is to treat one 
to two grams of the rubber with the acid-ether reagent until 
this reagent penetrates throughout the mass. The progress of 
the action, in presence of litharge, is easily followed by the 
change in color. The change is usually completed in a day. 
The rubber mass can then be removed or the ether evaporated. 
The mass is next washed in running water and dried. It is then 
ready for acetone extraction and the combined sulphur esti- 
mated in the residual rubber. If mineral sulphates are absent, 



FREE SULPHUR— MINERAL FILLERS 329 

the sulphur in the extracted rubber may be considered as organ- 
ically combined sulphur. It is safer to begin with two samples 
and to estimate the total free and combined sulphur in one and 
free sulphur in the other. The above process appears to be 
desirable where there are large quantities of free sulphur and 
accelerator. In the opposite instance the method of Stevens is 
perfectly satisfactory. 

MT. PROSPECT LABORATORY METHODS OF ANALYSIS. 

The methods employed in the Mt. Prospect Laboratory 
Department of Water Supply, Gas and Electricity of the City 
of New York, possess novel features introduced by Frank 
Gottsch. These methods are as follows: 

Free Sulphur. — The dried acetone extract is entirely 
transferred to a 60 c.c. iron or nickel crucible by acetone, chloro- 
form or benzol, and the solvents evaporated off on the steam 
bath and 6 grams of potassium carbonate and four grams of 
sodium peroxide are added. Mix, cover, heat at low tempera- 
ture over asbestos shield to avoid sulphur fumes, until the mix- 
ture fuses, then bring to quiet fusion for 15 to 20 minutes. 
Avoid rapid heating and explosion and rotate the melt while 
solidifying. When cool put crucible and cover into a casserole 
with 200 c.c. of water, add five to ten c.c. bromine water and 
boil melt till dissolved. Settle, decant, filter and wash through 
thick filter with hot water. Cool, acidify filtrate with dilute 
hydrochloric acid, make up to 400 c.c. and precipitate boiling 
with ten c.c. of ten per cent, solution of barium chloride. 

Mineral Fillers.— A one-gram sample is extracted by ace- 
tone for four hours and the rubber dried in the water oven at 
100 degrees C, until the odor of acetone is gone. Transfer 
the sample to a 100 c.c. beaker, burn the thimble to ash and add 
it to the beaker. Add 50 c.c. of clear molten salol and heat the 
beaker on the hot plate at a temperature of not less than 120 
degrees, nor more than 150 degrees C, stirring occasionally until 
the rubber is apparently dissolved. After settling, transfer the 
liquid to a 200 c.c. beaker and if the residue in the small beaker 
contains particles of undissolved rubber more salol is added and 
solution completed. Stir two c.c. of a one per cent, solution of 
soluble cotton in amyl acetate into the warm liquid in the 200 
c.c. beaker, cool and add redistilled turpentine until a good 



330 ANALYSES OF RUBBER 

"flock" has formed, adding at least 75 c.c. of turpentine with 
constant stirring. Allow the liquid to stand until the flock 
settles. The supernatant liquid is decanted and filtered by suc- 
tion through an alundum crucible placed in a Spencer holder. 
Wash the flock by decantation with turpentine, filtering the lat- 
ter; transfer the whole to the crucible, then dissolve carefully 
in a few c.c. of acetone, and wash the fillers with acetone, being 
careful not to allow the fillers to cover and clog the sides of 
the crucible. All beakers and the crucible are to be thoroughly 
washed with acetone. Dry to constant weight at 105 to 110 de- 
grees C, cooling in a desiccator. Evaporate all the filtrate and 
washings, transfer to a weighed porcelain dish, burn off the or- 
ganic matter. Add weight of residue to that of the fillers in the 
crucible and calculate as "mineral fillers." 

Foreign Alcoholic Potash Extract. — The dry rubber 
residue from the acetone extract is extracted with 50 c.c. of 
alcoholic potash, stoppered, in an air oven kept between 105 and 
110 degrees C, for four hours. Cool, filter and wash the. residue 
clean with hot absolute alcohol. Precipitate potassium chloride 
by acidifying filtrate strongly with hydrochloric acid, settle, fil- 
ter and wash with hot chloroform and evaporate the filtrate on 
a steam bath till odor of hydrochloric acid just disappears. Take 
up residue with chloroform, filter and wash with hot chloroform 
into a beaker, and evaporate to dryness. If the residue is not 
oily or greasy to touch, it may be disregarded. If oily or greasy 
the residue is washed with small portions of 88 degrees Baume 
naphtha, filtered through a washed plug of cotton into a small 
weighed beaker, evaporated and dried in water oven at 95 to 
100 degrees C. in 15-minute periods until the weight is con- 
stant, or increases. The result is calculated as "foreign alcoholic- 
potash extract." 

Vulcanized Rubber Gum by Weight. — Subtract the sum 
of the percentages of free sulphur, organic acetone extract, min- 
eral fillers and corrected foreign matter from 100 per cent. The 
balance is the vulcanized rubber gum by weight. 

Vulcanized Rubber Gum by Volume. — Multiply the per- 
centage by weight of vulcanized rubber gum by the specific grav- 
ity. The product is that specified by the term vulcanized rub- 
ber gum by volume. 



TOTAL SULPHUR IN RUBBER 331 

The method for free sulphur is designed to obviate abso- 
lutely the influence of organic matter by its complete removal. 
Concerning estimation of mineral fillers, it is found that salol 
will dissolve soft rubbers in less than an hour and vulcanite in 
from two to three hours. Owing to the condition of extreme 
fineness met with in many of the mineral fillers of rubber a 
coagulant is necessary to filter them off, even through an alun- 
dum crucible. Such a coagulant is soluble cotton dissolved in 
amyl acetate. Turpentine satisfactorily reprecipitates the soluble 
cotton used to form a flock suitable for filtration. 

Determination of Total Sulphur in Rubber. — The fol- 
lowing method was devised by Dr. Ludwig Rosenstein : 

Weigh out exactly 0.5 grams of the finely ground sample in 
a 300 c.c. Erlenmeyer flask. Add 15 c.c. of a saturated solution 
of arsenic acid, 10 c.c. of fuming nitric acid and 3 c.c. of satu- 
rated bromine water. Cover with a watch glass and boil until 
the sample is completely oxidized and a clear solution is ob- 
tained, adding more fuming nitric if necessary to complete the 
oxidation. Evaporate to syrupy condition, then add a few crys- 
tals of potassium chlorate to insure complete oxidation and to 
expel oxides of nitrogen. Continue the evaporation almost to 
dryness to insure complete expulsion of oxides of nitrogen. 
Cool and take up with 50 c.c. of 10 per cent, hydrochloric acid, 
heat on steam bath until solution is complete, filter to free from 
any insoluble matter and dilute the filtrate to about 300 c.c. 
From this solution the sulphur, which has been converted to sul- 
phate, may be precipitated with barium chloride. Filter and 
weigh, observing the usual procedure and take special precaution 
that precipitate be filtered from the hot solution and washed 
with hot water to remove any lead salts. 

The function of the arsenic acid is to raise the boiling point 
of the solution during the oxidation, thus making it more com- 
plete and rapid. It may be prepared by adding C. P. arsenic 
oxide to boiling water until boiling point of the solution is 140 
degrees C. 

This method has been found rapid and accurate to within 
less than 0.1 per cent, on rubber mixings, both cured and un- 
cured containing known amount of sulphur, with and without 
various compounding ingredients. 



332 ANALYSES OF RUBBER 

ELECTROLYTIC METHODS. 

Electrolytic Method for Lead and Zinc in Vulcanized 
Rubber. — The following method is by Elmer D. Donaldson. 
The portion relating to the deposition of zinc on platinum direct 
is adapted from a method by W. S. Kimley. 

Donaldson's method consists of digestion of the ash in nitric 
acid and precipitation of lead as peroxide (Pb0 2 ), followed by 
evaporation and precipitation of zinc as metal, both on platinum. 
The electrolytic apparatus was equipped with a rotating electrode 
and pole-reversing switch. The larger electrodes were of plati- 
num gauze lyi inches wide by 2 inches high, sand blasted, and 
the rotating gauze x / 2 inch wide by 2 inches high. The apparatus 
was connected to a 110-volt direct current generator and lamp 
resistance. 

Lead. — Weigh one gram rubber, wrap in a seven-centimeter 
ashless paper and incinerate in a 20 to 30 c.c. porcelain crucible. 
Brush the ash into a 200 c.c. electrolytic beaker, add 25 c.c. con- 
centrated nitric acid, and digest on hot plate for 15 minutes. 
Boil to expel nitrous fumes and dilute to about 125 c.c, having 
solution at 158 degrees to 176 degrees F. Electrolyze with 
rotating cathode, using direct current of two to three amperes. 
The lead will appear on the large gauze anode as peroxide, black 
when in large amounts, bronze colored when in small amounts. 
Electrolyze 30 minutes and wash anode thoroughly with water 
to remove mechanical impurities, then with alcohol and ether. 
Dry for 30 minutes at 338 degrees F. Weigh as peroxide of 
lead (PbO a ) and for convenience calculate to litharge (PbO), 
using the factor 0.933. No metals present in rubber mixings will 
interfere with this determination. 

Zinc. — Wash the solution and the insoluble matter from the 
electrolytic beaker, from which the lead has been removed, into 
a litre beaker. Add five c.c. of concentrated sulphuric acid, 
evaporate dry, and drive off most of the sulphuric acid. This 
is done to insure complete removal of nitric acid, which would 
interfere with the electro deposition of zinc. After evaporation, 
cool and digest residue, which usually contains considerable in- 
soluble, with 50-75 c.c. water. The zinc is now present as zinc 
sulphate and is readily soluble. Filter and wash. If the zinc 
oxide content is known to be low use entire filtrate, but if 20 



INSULATION SPECIFICATION 333 

per cent, or over, catch nitrate in 200 c.c. volumetric flask. Make 
up to mark and take 50 c.c. 

Wash this portion of solution representing 0.25 grams of 
rubber sample into a 200 c.c. electrolytic beaker. Add consider- 
able excess of saturated solution of sodium hydroxide over that 
necessary to redissolve the zinc hydroxide. Electrolyze at ordi- 
nary temperature at 2 to 2.5 amperes, rotating the anode for 20 
minutes. Remove and wash with water, alcohol and ether. Dry 
at 212 degrees F. for a few minutes, cool and weigh. 

Zinc is deposited on the cathode and is weighed as metal. 
The weight of zinc is calculated to zinc oxide. Aluminum will 
not interfere even if the solution is gelatinous from the precipi- 
tated aluminum hydroxide. In event that iron is present, filter 
off the iron hydroxide after adding just enough sodium hydrox- 
ide solution to insure solution of the zinc hydroxide. Then add 
further sodium hydroxide solution to this filtrate. Lead peroxide 
and zinc can be dissolved from the platinum gauze by concen- 
trated nitric acid saturated with tartaric acid. 

JOINT RUBBER INSULATION COMMITTEE'S SPECIFICATION 

FOR 30 PER CENT. HEVEA RUBBER COMPOUND. 

(chemical clauses.) 9 

1. A 30 per cent, fine Para or best quality plantation Hevea 
rubber compound with mineral fillers shall be furnished. It 
shall contain only the following ingredients: (1) rubber; (2) 
sulphur; (3) inorganic mineral matter; (4) refined oil paraf- 
fin or ceresin. 

2. The vulcanized compound shall conform to the fol- 
lowing requirements, when tested by the procedure of the Joint 
Rubber Insulation Committee, results being expressed as per- 
centages by weight of the whole sample. 

REQUIREMENTS INDEPENDENT OF THE AMOUNT OF 
RUBBER FOUND. 

Maximum Minimum 

Rubber 33 30 

Waxy hydrocarbons 4 

Free sulphur .". 0.7 

Red lead, carbon, or organic fillers shall not be present. 



'Joint Rubber Insulation Committee Report in "The Journal of In- 
dustrial and Chemical Engineering" (March, 1917). The procedure is 
outlined elsewhere in this chapter. 



334 ANALYSES OF RUBBER 

REQUIREMENTS DEPENDENT UPON AMOUNT OF 
RUBBER FOUND. 

(Requirements for intermediate percentages shall be in proportion to the 
percentage of rubber found.) 

30 Per Cent. 33 Per Cent. 

Rubber Compound Rubber Compound 

Maximum Minimum Maximum Minimum 

Saponifiable acetone extract.. 1.35 0.55 1.50 0.60 

Unsaponifiable resins 0.45 0.50 — 

Chloroform extract 0.90 .... 1.00 

Alcoholic potash extract 0.55 — 0.60 — 

Total sulphur (Note 2) 2.10 .... 2.30 

Specific gravity 1.75 — 1.67 

3. The acetone solution shall not fluoresce. 

4. The acetone extract (60 c.c.) shall be not darker than 
a light straw color. 

5. Hydrocarbons shall be solid, waxy and not darker than 
a light brown. 

6. Chloroform extract (60 c.c.) shall be not darker than 
a straw color. 

7. Failure to meet any requirement of this specification 
will be considered sufficient cause for rejection. 

8. Contamination of the compound, such as by the use of 
impregnated tapes, will not excuse the manufacturer from con- 
forming to this specification. 

Note 1. This specification shall be supplemented by appro- 
priate clauses relating to tensile strength, elasticity, electric 
insulation resistance and dielectric strength. (See the Wire and 
Cable Specifications of the American Society for Testing Mate- 
rials, the Association of Railway Electrical Engineers, etc., for 
examples of such clauses.) 

Note 2. The limit on total sulphur may be omitted at the 
option of the purchaser. 

Experience has shown that compounds of the grade which 
contain only good Hevea rubber, may be relied upon to be more 
permanent than those made of rubber of other grades. It is not 
affirmed by the committee that a compound which conforms with 
this specification is necessarily permanent, or that a better com- 
pound cannot be made, but it is believed that enforcement of 
the specification will limit the use of inferior materials and that 
it will put the manufacturers more nearly upon equality of en- 
deavor, where they can use their experience to obtain the best 



INSULATION SPECIFICATION 335 

results. Used in connection with the analytic procedure, the 
specification will enable purchasers to order a good compound 
and to ascertain, with a greater certainty than heretofore, 
whether the material received represents the compound specified. 
The term Hevea applied to rubber means rubber from the 
Hevea Brasiliensis tree, whether wild or cultivated and regard- 
less of the locality in which it has been grown. Para rubber is 
Hevea rubber of the kind originally shipped from the port of 
Para, Brazil, and comes in several grades. The rubber required 
by this specification should be Hevea rubber of good quality, 
such as fine Para or best quality plantation rubber. 

Carbon is excluded, not only because it is considered, by 
some purchasers, to be deleterious, but because it interferes with 
the determination of rubber hydrocarbons. 

Red lead is excluded because of the possibilities of its dele- 
terious effects on rubber. 

Ozocerite is prohibited because the acetone extract obtain- 
able from it interferes with the separation of the acetone extract 
obtainable from the rubber, thereby vitiating the assay of the 
rubber extract. This prohibition is unimportant to the manu- 
facturers, as ceresin, which is permitted, is the essential con- 
stituent of ozocerite. 

An upper limit is placed upon the rubber in order to pre- 
vent the attainment of electrical and mechanical strength by the 
use of an extra quantity of inferior rubber whose lasting qual- 
ities might not be satisfactory. 

The hydrocarbons are limited, owing to their tendency to 
separate from the compound and thus cause porosity. 

The free sulphur is limited because an excessive amount 
may be deleterious. 

The maximum limit on the saponifiable acetone extract is to 
prevent the use of raw or reclaimed rubber with high saponifi- 
able extract. The medium limit assists in forcing the use of 
Hevea rubber, since it is characteristic of the acetone extract 
from Hevea to be largely saponifiable. 

The unsaponifiable resins are limited because a low propor- 
tion of unsaponifiable resins is characteristic of Hevea rubber. 
A high result might be due to the presence of reclaimed rubber. 



336 ANALYSES OF RUBBER 

The chloroform extract is limited ; first, to prevent the 
use of bituminous substances, and, second, to limit depoly- 
merized and under-cured rubber. 

The alcoholic potash extract is limited to prevent the use 
of saponifiable rubber substitutes. 

The specific gravity is limited to reconcile the specification 
of ingredients by weight with the practice of purchasing 
material by volume. 

Fluorescence of the acetone solution is prohibited, as it 
indicates the presence of bituminous substances, rosin oil or 
mineral oils. 

The color of the acetone extracts is specified to conform 
with the normal color of the extracts of Hevea rubber. A 
darker color indicates adulteration or an inferior grade of 
rubber. 

The hydrocarbons are required to be solid in order to 
prevent the use of oils and paraffin of low-melting point. The 
shade required is that obtained from paraffin wax or ceresin. 
Liquid hydrocarbons indicate reclaimed rubber softened with 
mineral oil, or paraffin of low-melting point. 

The color of the chloroform extract is specified to con- 
form with the color of dissolved gum in small quantities. 
The presence of bituminous substances would be indicated 
by a brown or black color. 

It would be desirable that the sulphur of vulcanization be 
limited to exclude reclaimed rubber, which contains the sul- 
phur of its previous vulcanization, but the committee has not 
yet developed an acceptable method for determining this 
quantity. It is, therefore, confronted with the choice of either 
placing a limit on the total sulphur or giving up the attempt 
to exclude shoddy by sulphur limitation. Option is, therefore, 
given to the purchaser to insert or omit the limit on total 
sulphur. Such insertion will at times exclude reclaimed rub- 
ber and the committee believes it possible to make a suitable 
compound with this limitation. The committee thinks that 
a sulphur limit positively excluding reclaimed rubber, would 
place too great a hardship, in other ways, on the manufac- 
turers. Where the specification is used with no total sulphur 
limit, the use of many kinds of, or much reclaimed rubber, 



PHYSICAL TESTING OF RUBBER 337 

will be guarded against by the limits of the various compo- 
nents of the acetone extract. When the limitation on total 
sulphur is omitted, sulphur-bearing fillers, which possess cer- 
tain advantages, may be used. 

This specification should be supplemented by appropriate 
elasticity and tensile strength tests, in order to add to the 
assurance that good rubber has been used and that the vul- 
canization process has been properly carried out; also by 
appropriate electric stress and resistance tests, to assure proper 
insulating qualities and homogeneity of structure. The exact 
value of the limits for these tests will depend upon the use to 
which the material is to be put. 

The Joint Rubber Insulation Committee's chemical clauses, 
or analytical procedure for insulation, have been adopted by 
the following: 

American Electric Railway (Engineering) Association : 
Standard Specification for Rubber Insulated Wire and Cable. 

America Society for Testing Materials: Proposed Speci- 
fications for Insulated Wire and Cable; 30 per cent. Hevea 
Rubber. 

Association of Railway Electrical Engineers : Standard 
Specifications for Wire and Cable. 

Interborough Rapid Transit Co., Motive Power Depart- 
ment, New York : Specification No. 2. 

New York Central Railroad Co., Electrical Department: 
Specification No. 300. 

Panama Canal : Office of General Purchasing Agent, Cir- 
cular No. 1,038. 

Signal Corps, U. S. Army: General Specification No. 
581-A. 

PHYSICAL TESTING OF RUBBER GOODS. 

There is a great variety of special appliances that afford 
really valuable tests as to the durability, tensile strength and 
wearing quality of certain kinds of goods. As a rule, these 
aim to subject the vulcanized article to conditions 1 equivalent 
to those to which it will be subjected in actual service. For 
rubber boots and shoes, for example, a machine is employed 
which bends the shoe exactly as it is bent when the wearer 
is walking, and at the same time gives a friction motion on 



338 ANALYSES OF RUBBER 

the sole. This is run at high speed, so that a week's wear on 
the machine corresponds to a month of service in actual use. 

A machine is also used for testing air-brake hose which 
counterfeits the swing and kinking motion that the hose gets 
in actual service. The hose which stands this sort of usage 
longest is supposed to be adapted to endure the longest time 
in actual use. 

Tires, both pneumatic and solid, are tested by being put 
on a wheel rim and run the equivalent of hundreds and thou- 
sands of miles over roughened surfaces upon which they are 
pressed by a lever carrying heavy weight. These mechanical 
contrivances are valuable in showing the severe usage that 
rubber will often stand, but none of them are exact parallels 
to absolute service, for as a rule they are more severe, par- 
ticularly in the intense heating that may come to the rubber 
from high speeds and great friction. 

Manufacturers and purchasers of rubber goods have also 
many simple and excellent tests for approximating the value 
of the rubber. In belt and hose covers and tubes, a strip of 
the rubber is removed from the fabric and stretched to show 
its tensile strength. The fabric is also pulled apart, and the 
integrity of the friction proved by the way it resists such 
separation. Rubber springs sometimes have been placed 
under a steam hammer, which was allowed to drop upon them, 
the results being noted and that compound standing up 
longest being considered the best. 

STANDARD METHODS FOR PHYSICAL TESTING. 

The following methods are standard for the physical 
examination of vulcanized rubber goods as specified by the 
Board of Estimate and Apportionment of New York City: 

Sampling. — The contracting department shall select and 
take all samples for testing. The number of samples and the 
quantity to be taken from the deliveries will depend upon the 
size of the articles and the quantity delivered. 

Samples shall fairly represent the delivery, and pieces 
shall be taken from not less than one per cent, of the number 
of units delivered. 

Averages. — The results of tensile strength, elongation and 
set tests as reported, shall be the average obtained from the 



METHODS FOR PHYSICAL TESTING 339 

samples received by the laboratory. Not less than three test 
pieces from each sample shall be tested and their results taken 
in calculating the average unless some individual result is appar- 
ently in error, in which case a retest shall be made. 

Temperature of Testing Room. — Physical tests of rubber 
shall be made with the temperature of the air not lower than 
65 or higher than 90 degrees F. 

Time. — All measurements of time shall be taken with an 
accurate stop watch. 

preparation of test pieces. 

Test pieces of rubber shall be stamped out with a die, when- 
ever practicable to do so. 

Tensile Strength, Elongation and Set Test Pieces. — 
Test pieces of rubber for tensile strength, elongation and set 
tests shall be cut out with a die, either of the constricted bar 
or ring type. The same test piece shall be used for making all 
three tests. When the bar-test piece is prepared a die should be 
used that will make the constricted part of such a width that the 
cross section will be approximately one thirty-second of a square 
inch. 

All pieces for these tests shall have the backing entirely 
removed, and any corrugations or irregularities of any kind 
shall be accurately buffed off, to make a uniformly smooth 
surface. 

Test pieces which have become burnt in buffing shall be 
discarded. 

Test pieces shall be kept constantly wet during the 
buffing. 

Test pieces of rubber valves and odd-shaped rubber arti- 
cles shall, whenever possible, be cut down on a lathe to an even 
thickness of not more than one-eighth inch and then cut out to 
shape for testing with a die. 

If it is necessary to use naphtha to remove the backing 
or to separate the rubber from the plies, the naphtha shall be 
what is technically known as 76-degree Baume, free from oil. 

When naphtha has been used the test pieces shall be 
allowed to remain at rest for not less than one hour before 
testing. 



340 ANALYSES OF RUBBER 

In all cases where backing is removed and buffing done, the 
test pieces shall remain at rest for not less than ten minutes 
before testing. 

Friction Test Pieces. — Test pieces for friction or adhe- 
sion tests shall be cut and prepared as follows: 

All kinds of hose, round packing and similar articles shall 
be cut transversely unless the diameter is so small that a prac- 
tical measurement cannot be taken, in which case the test pieces 
shall be cut longitudinally. 

Belting, packing or gasket material may be cut in any 
direction. 

Test pieces from washers, ferrules (sleeves), molded gas- 
kets and other odd-shaped articles shall be prepared in the 
manner called for in the unit specification, if it is impracti- 
cable to prepare them in accordance with these rules. 

Cotton rubber-lined hose test pieces and braided hose test 
pieces shall be accurately cut transversely two inches wide and 
full length of the circumference. They shall be cut through the 
walls so that they can be laid out flat the full length of the piece. 
One-quarter inch of the rubber lining shall be carefully and 
cleanly trimmed off on each side, without injuring the fabric, 
leaving a strip of rubber lining one and one-half inches wide 
undisturbed on a strip of cover two inches wide. A separation 
between lining and cover of this strip shall be started for about 
one and one-half inches. 

Test pieces of wrapped hose, round packing and similar 
articles shall be accurately cut transversely one inch wide and 
left circular, to permit sliding on to a mandrel. A separation 
between the rubber and the fabric or between the layers in 
accordance with the test to be made shall be started full width of 
the piece and far enough distant to permit proper fastening of 
clamps or hooks, as the case may be. 

Solid round packing and similar articles shall have a core 
drilled out for the mandrel. 

Fabric-backed rubber packing test pieces shall be prepared 
in the same manner as for cotton rubber-lined hose, except that 
if the rubber part is more than one-eighth inch thick, the test 
piece shall be prepared exactly opposite, leaving a strip of sheet- 
ing one and one-half inches wide on a strip of rubber two inches 



METHODS FOR PHYSICAL TESTING 341 

wide. A separation between sheeting and rubber shall be started 
for about one and one-half inches. 

Belting test pieces shall be accurately cut one inch wide and 
shall be stripped down to all but two plies, and a separation of 
the two plies started for about one and one-half inches. 

All pieces of flat material, such as packing, gasket, belting, 
etc., shall be cut not less than 12 inches long whenever possible. 

DETERMINATION OF TENSILE STRENGTH. 

The determination of tensile strength of the rubber com- 
pound shall be made as follows: 

Apparatus. — All tensile strength tests shall be made on an 
apparatus the general design of which conforms to the Schopper 
machine. 

Grips. — When bar-test pieces are used, the grips for hold- 
ing the test pieces shall be such that they will tighten automati- 
cally, exerting a uniform pressure proportionate to the applied 
tension across the full width of the piece, regardless of any 
variation in the thickness of the rubber. 

Ring-test Pieces, — These shall be placed over the revolv- 
ing rollers of the Schopper machine. 

Marking Bar-test Pieces. — The bar-test pieces shall be 
stamped in center portion with two lines two inches apart, using 
a rubber ink-pad stamp. The distance between the outside edges 
of these stamped lines shall be accurate to one one-hundredth 
of an inch. 

Measurement of Bar-test Pieces. — The width and thick- 
ness of the test pieces shall be accurately determined at three 
points equidistant between the marks, a spring gage or ratchet 
stop micrometer being used. 

Measurement of Ring-test Pieces. — The width and thick- 
ness of the test ring shall be accurately determined at not less 
than four opposite points on the ring, care being taken to get 
the minimum cross section as near as possible, the area of which 
shall be used in computing the tensile strength. 

Breaking. — Bar-test pieces shall be tightly fastened in the 
jaws and brought just taut. The machine shall then be started 
and the speed so regulated throughout the entire test that the 
jaws separate at the uniform rate of 20 inches per minute. 



342 ANALYSES OF RUBBER 

The number of pounds necessary to break the test piece 
shall be read to the nearest tenth of a pound and computed to 
pounds per square inch, using the measurements nearest to the 
break. 

When breaking the ring-test piece the ring shall be slipped 
over the revolving bearing provided for it and the procedure 
continued exactly as for the bar-test piece, the speed being so 
regulated that it will give an equivalent elongation of test piece 
per minute. 

TENSILE STRENGTH ACROSS THE SEAM. 

Bar- and ring-test pieces shall be prepared as usual, except 
that the seam shall not be buffed off. 

In cutting, the seam shall be centered in the middle of the 
bar-test piece, at right angles to the axis, as nearly as possible. 

The center of the seam shall be made to lie along a diameter 
of the ring-test piece as nearly as possible. 

The calculation shall be based on the average cross section 
in both kinds of test pieces in the usual manner, but excluding 
the cross section of the seam or seams. 

ELONGATION AT THE BREAKING POINT. 

The elongation at the breaking point shall be accurately de- 
termined during the tensile strength test as follows : 

On the bar test a rule graduated to hundredths of an inch 
shall be kept opposite the two marks and the distance the out- 
side edges of these two marks are apart at the instant of break- 
ing shall be noted. 

This distance shall be computed into per cent, of elongation ; 
i. €., if the marks are twelve inches apart at the break, that piece 
would have 500 per cent, elongation. 

Ring-test Pieces. — These shall have the elongation read to 
the nearest whole per cent, from the automatic record on the 
stretch tapes. 

determination of set. 

The determination of set shall be on the test piece as broken 
in the tensile strength test not less than one nor more than one 
and one-half minutes after breaking. Time shall be taken 
with a stop watch. 



TESTS OF AIR-BRAKE HOSE 343 

Bar-test Pieces shall have the distance from the outside of 
the line to the furthest broken point measured carefully along 
the axis on one broken portion to the nearest one-hundredth 
inch and in the same manner from the corresponding nearest 
broken point on the other portion. The sum of these two 
measurements, minus two inches, is the actual set, and shall be 
computed to percentage of the elongation at rupture to the 
nearest tenth per cent. 

Ring-test Pieces shall have the inner circumference care- 
fully measured around a solid disk of the same diameter as the 
inside diameter of the original ring. The increase in length 
(actual set) is read to the nearest half per cent., divided by the 
per cent, elongation at rupture, and the result recorded to the 
nearest tenth per cent. 

DEFECTS. 

If the break occurs outside the gage marks on the bar- 
test piece during the tensile strength test,, the specimen shall 
be considered as defective for any determination, and another 
test made. 

The broken surfaces of both test bars and test rings shall 
be examined for flaws or defects, and if the results of the 
tests confirm the observation of flaws the test pieces shall be 
replaced by others. 

PHYSICAL PROPERTIES AND TESTS OF AIR BRAKE AND 



10 



SIGNAL HOSE. 

Hose shall be subjected to the following tests, which must 
be made at a room temperature of not less than 65 degrees F. 

Test Specimen. — A hose shall be selected at random and 
a section five inches cut from one end. Two sections, each 
one inch long, shall be cut from the 5-inch section for mak- 
ing friction, stretching and tensile tests ; the remaining three- 
inch section shall be used for making additional tests, which 
may be desired on the tube and cover. Stretching and ten- 
sile test specimens shall be cut from the tube and cover with 
a die to standard dimensions specified. 



10 From Master Car Builders Association Standard Specifications, 
1915. 



344 ANALYSES OF RUBBER 

Friction Test. — The quality of friction shall be deter- 
mined by suspending a 20-pound weight from the separated 
end of the duck of one of the 1-inch test specimens previously 
described, the force being applied radially. The separation 
shall be uniform and regular, and the average speed shall not 
exceed 8 inches in 10 minutes, the distance being measured 
while the weight is still in place. 

Stretching Test. — Test specimens from tube and cover 
will be quickly stretched until the 2-inch marks are 10 inches 
apart and immediately released. They will then be re-marked 
as at first within 10 seconds after starting to release and again 
stretched to 10 inches between the new marks, remaining so 
stretched for 10 minutes. The specimens shall then be com- 
pletely released, and within 30 seconds after starting to 
release the distance between the marks last applied will be 
measured, and the initial set must not be more than % inch. 
At the end of 10 minutes the distance between the marks will 
again be measured, and the final set must not be more than 
}i inch. These test specimens may be cut from the tube and 
cover of the friction-test specimen, but shall not be used for 
tensile test. 

Tensile Strength. — Test specimens from tube and cover 
shall be pulled in a tensile machine with a test speed of 20 
inches per minute. The inner tube must have a tensile 
strength of not less than 800 pounds or more than 1,200 
pounds per square inch, and the cover not less than 700 pounds 
or more than 1,100 pounds per square inch. The elongation 
shall be such that the marks, originally two inches apart, 
stretch to at least 10 inches before specimen breaks. If the 
tensile strength in pounds per square inches is greater than 
that required, the sample may be accepted, providing the per 
cent, increase in elongation is equal to or greater than the 
per cent, increase in tensile strength in pounds per square 
inch above the maximum figure. 

Porosity Test. — The remaining 17 inches shall be 
mounted and placed in a test rack; the circumference will be 
measured and the hose filled with air at 140 pounds pressure 
per square inch; the rubber cover shall be cut from clamp 



MECHANICAL AND CHEMICAL PROPERTIES 345 

to clamp (taking care not to injure the duck) and this pres- 
sure maintained for five minutes. At the end of this time 
the hose will be submerged in water to determine whether 
the inner tube is porous. The escape of air through the tube 
shall be distinct enough so that porosity will not be confused 
with the escape of air which is confined in the structure of 
the hose. In the event the hose fails on bursting test at the 
point at which cut was made for porosity test and a satis- 
factory hydraulic test is not obtained, the porosity and hy- 
draulic test will be repeated on another piece of hose. 

Bursting Tests. — The section of hose, which was used 
for porosity test, shall then be subjected to a hydraulic pres- 
sure of 200 pounds per square inch, under which pressure it 
shall not expand in circumference more than ^4 inch for air- 
brake hose and {% inch for air-signal hose, nor develop any 
small leaks or defects. After the above test, this section shall 
then stand a hydraulic pressure of 500 pounds per square inch 
for 10 minutes, without bursting or developing any small 
leaks or defects, after which the hydraulic pressure shall be 
increased to a minimum of 700 pounds per square inch with- 
out bursting, at the rate of not less than 100 or more than 
200 pounds per five seconds. 

RELATIONSHIP OF MECHANICAL TO CHEMICAL 
PROPERTIES. 11 

From experiments made there is no question that the com- 
bined sulphur at "optimum" cure in the case of Hevea plan- 
tation rubber is a remarkably constant quantity, equal on the 
average to approximately 2.8-3 per cent. Where more than 
this amount of combined sulphur has been found, either the 
method of vulcanization is at fault or the means of determin- 
ing the "optimum" cure are inaccurate. In this connection 
it is necessary to point out that in the case of very soft, low- 
grade rubbers it is difficult to judge of the "optimum" cure, 
and there is always the tendency to increase the cure to be- 
yond the "optimum" point in the hope of thereby improving 
the physical or tensile properties of the product. In the case 
of any good grade of Hevea plantation rubber there is no such 



11 Doctor D. Spence, "On the Relationship of Mechanical to Chemi- 
cal Properties." "India Rubber Journal," December 9, 1916. 



346 ANALYSES OF RUBBER 

difficulty, however, and where more than 2.8-3 per cent, of 
combined sulphur is reported in this case, either the sample 
is over-cured, or what amounts to the same thing, vulcaniza- 
tion has not been properly carried out. With proper meth- 
ods of vulcanization, and with the requisite experience in 
the judging of the proper cure, the combined sulphur at 
"optimum" cure should never greatly exceed the figures we 
have given. It should be pointed out, however, that if the 
time of cure required to produce the "optimum" result is 
extended, the chances are an increase in the amount of the 
combined sulphur at the "optimum" point over the figures 
we have given will be found. Depolymerization, requiring an 
increase in cure to bring the rubber up to apparent physical 
"optimum" leads to an increase in the combined sulphur con- 
siderably over the amount which we have given. The rubber 
in this case is, nevertheless, over-cured, and where the vul- 
canization of the rubber is carried out scientifically, in a 
minimum of time, and with the least possible injury to the mole- 
cule, the combined sulphur at "optimum" cure will never be 
found to exceed three per cent. 

Whether these figures obtain for rubbers of different 
botanical origin or not we have not sufficient analytical evi- 
dence at present to say. The constancy of this result is 
deduced from experiments made on Hevea Brasiliensis rubber 
only. The relation between the rubber and combined sulphur 
at correct cure is so constant that it is regarded as represent- 
ing a more or less definite compound of rubber and sulphur 
to which a formula may be assigned on the assumption that 
partial valencies of the rubber aggregate have not all the 
same affinity for sulphur. 

It may be of interest to record the fact that we have 
observed that the point at which the physical properties of 
pure balata on vulcanization suddenly change to more nearly 
resemble those of rubber, corresponds very closely with a 
combined sulphur content of three per cent. If pure balata 
is mixed with a little sglphur and a suitable catalyst, which is 
essential to its proper vulcanization, it will be found that 
when about three per cent, of sulphur has combined with the 
balata, the physical properties of the vulcanized balata change 



COEFFICIENT OF VULCANIZATION 347 

from those of a hard, inelastic product, more like hard rubber, 
to a pliant, semi-elastic product, more nearly resembling soft 
vulcanized india rubber. This phenomenon is exceedingly 
remarkable and interesting, as the transition point in the 
physical characteristics of balata on vulcanization occurs at 
about the same degree of chemical vulcanization as corre- 
sponds to the "optimum" cure of vulcanized india rubber. 
This has given rise to a number of experiments by us, with a 
view to converting balata into rubber and vice versa, some 
of which have led to exceedingly interesting results. 

COEFFICIENT OF VULCANIZATION AND THE STATE OF CURE. 

Henry P. Stevens states 12 that if physical tests on vulcan- 
ized rubber are to be of practical value in deciding the manu- 
facturing value of any particular specimen, these tests must be 
carried out on a rubber cured suitably to meet manufac- 
turing conditions; or, if on a rubber cured beyond this stage 
(over cured), there must be available some method by which 
the tests on the over-cured rubber may be correlated to tests 
on correctly cured rubber. No such method of calculation 
is at present available, as the necessary relationship has not 
been worked out between stress-strain curves and coefficient 
of vulcanization. A correctly cured rubber is one fully cured 
from the manufacturer's standpoint, not beyond that point at 
which aging is satisfactory. Otherwise the specimen is over- 
cured. 

Rubber is a colloid, and shows the phenomena of hys- 
teresis. Its physical properties at any moment depend partly 
on its previous history. It is therefore obvious that no con- 
clusions should be drawn from any stress-strain curve with- 
out taking into consideration the previous history of the speci- 
men. Dr. Stevens agrees with the statement of Dr. de Vries 
that "the percentage of combined sulphur is quite independent 
of the state of cure as expressed by the position of the stress- 
strain curve," but adds that the "state of cure" cannot be ade- 
quately expressed under present conditions by the stress- 
strain curve. It may, however, be possible when the "stand- 



'"India Rubber Journal." February 10, 1917. 



348 ANALYSES OF RUBBER 

ard curve" or other methods are correlated to manufacturing 
conditions and the tests carried out on rigidly standardized 
lines. 

Vulcanization is essentially a chemical process; so also is 
the subsequent decomposition of rubber which has been over- 
cured, and hence the proportional relationship of rubber and 
sulphur in combination is the best guide for a stable product, 
the first essential in the manufacture of rubber goods. 

Discussing the case in which the "coefficient" (according 
to Stevens) may be wrong, but the mechanical properties 
correct, Schidrowitz and Goldsborough note that the question 
at issue is whether state of cure or correct cure is to be 
judged by the chemical or the mechanical properties of the 
vulcanized article — by sulphur combined with the rubber or 
by the stress-strain curve. Their answer is that ultimately the 
attributes or quality of vulcanized rubber must be judged by 
the physical or mechanical properties. 

Certain low-curing rubbers require, in order to acquire 
the necessary mechanical properties, a protracted cure, and in 
the course of such cure will combine with more than three per 
cent, of sulphur, and in general slow-curing rubbers deterio- 
rate more rapidly than rapid-curing goods, and will not age 
well because of the excess of combined sulphur, and possibly 
also by reason of the long heating necessary. 

The physical and mechanical effects which vulcanization 
has upon rubber are shown in the clearest manner by the 
stress-strain curve method, and there is no other known 
method whereby the mechanical aspect of vulcanization can 
be systematically and accurately followed' and measured. 

Regarding this method, its authors, Schidrowitz and 
Goldsborough remark : 

In view of the apparent lack of comprehension concern- 
ing stress-strain curves, we take this opportunity of briefly 
re-stating some of the more important points. 

1. The "type" of the curve is independent of the state of 
cure. It therefore connotes inherent properties. 

2. As the "type" varies for different rubbers, its deter- 
mination affords a valuable method of comparison in regard to 
important mechanical properties. 



SPECIFIC GRAVITY IN COMPOUNDING 349 

3. We obtain a graphic representation of the progress of 
vulcanization. 

4. We are able to cure to a definite mechanical condition, 
and to estimate the rate of cure necessary to attain that condi- 
tion. 

5. Having settled the position of the curve for a given rub- 
ber mixing we are able to control the vulcanization of the fac- 
tory product. 

Much else may be done with and deducted from the stress- 
strain curve method. In more propitious times the authors pro- 
pose to recur to the subject at length. 

While agreeing that stress-strain curves are of great value, 
intelligently applied, Dr. Stevens holds that the coefficient of 
vulcanization is the safest guide as to the state of cure. 

SPECIFIC GRAVITY IN RUBBER COMPOUNDING. 

The relation of bulk to weight depends on the specific 
gravity of the material and is of great importance in the rub- 
ber industry because it controls the number of pieces per 
pound in molded rubber goods, and the rubber-coated area ob- 
tainable per pound in the case of coated fabrics, from any 
given stock. 

The specific gravity of any substance is the particular ratio 
of its weight to that of an equal bulk of another substance 
taken as standard, or unit weight. For all solids and liquids, 
the standard substance of unit gravity is distilled water at 
62 degrees F. For gases the standard is hydrogen gas at 
the atmospheric pressure of the sea level. 

The method of determining specific gravities of solids 
depends on the fact that any insoluble substance immersed in 
water loses weight equal to the weight of the volume of water 
which it displaces. The means of ascertaining specific gravities 
vary according as the substance under examination is solid, 
liquid, or gaseous. 

In the case of solid bodies, not in powdered form, a bal- 
ance or other weighing apparatus is employed by which 
the weight of the material in air and its loss of weight in water 
may be determined. These values having been found experi- 
mentally, the specific gravity is ascertained by dividing the 
weight of the material in air by its loss of weight in water. 
For rapid determinations of specific gravity, special instru- 



350 ANALYSES OF RUBBER 

ments are often used; for example the spiral balance, or a 
direct reading instrument, known as a gravitometer. 

For materials in the form of powder the specific gravity 
bottle is used. This is of various forms, but is essentially a 
small glass-stoppered flask provided with a reference mark on 
the neck. A fine chemical balance is necessary to make the 
weights and the procedure is as follows 13 , for solids heavier 
than water: 

Weigh the flask filled to the mark with water, then place 
the substance, of known weight, in the flask, fill to the mark 
with water, and weigh again. The calculation of the speci- 
fic gravity will be : 

(Weight of substance in air) -|- (weight 

of flask and water) — (weight of flask 

and water and substance). 

Specific gravity = — 

(Weight of substance in air). 

It should be noted that specific gravity is not to be taken 
as a test for quality as applied to rubber compounds, but 
should be considered simply as a factor in the economy of 
any given stock. A practical application is found in estimat- 
ing the weight of a proposed article when its net cubical 
contents of stock is known. The weight for water of the 
cubical contents is ascertained by multiplying by 252.5, the 
weight in grains of one cubic inch of water. This product, 
multiplied by the specific gravity of any material, will give the 
weight of the object in that material. 



From Bailey's "Chemists' Pocket Book." 



CHAPTER XIX. 

PRIMARY PROCESSES, DIVISIONS OF RUBBER 
MANUFACTURE AND TYPICAL COMPOUNDS. 



WASHING, DRYING, MILLING, CALENDERING, 
AND SPREADING. 

The very first manufacturing process in the manipulation 
of rubber of any kind, and for any use, is that of cleansing. 
This is usually done by passing the gum repeatedly between cor- 
rugated rolls, while fine streams of water remove the various 
impurities that are exposed by the tearing action of the rolls. 
These impurities are bits of vegetable substances, earth, sand, 
etc. The old type of washer for removing these was a couple 
of corrugated rolls 6 or 8 inches in diameter, and 12 or 14 
inches in length. Modern methods, however, have introduced 
larger rolls, until today one machine, when it is the highest 
type of three-roll washer, will cleanse enough gum to keep a 
huge factory busy. 

There are also a number of enclosed washers of the masti- 
cator type that do excellent work and for some purposes are 
preferred to either the open roll or the hollander type of 
machine. 

Some rubbers are so full of sand that it is almost impossible 
to remove it wholly. For this purpose is used a tub with a false 
bottom made of fine wire, and also with a stirrer. "Thimbles," 
for instance, after being run through the washer, are put in the 
tub without any attempt at sheeting, and stirred until a large 
portion of the sand is removed. 

Another type of washer is one that is quite similar to a 
paper engine; in fact, paper engines are often used in rubber 
washing. The special value of this type is that the rubber in its 
movement about the tub is floated more or less, and the sand and 
earthy matters sink to the bottom, while the bark and vegetable 
matters can be seen and easily removed. 

351 



352 DIVISIONS OF RUBBER MANUFACTURE 

Some manufacturers, following Austin G. Day's ideas, have 
used alkaline solutions in washing certain gums, to neutralize the 
vegetable acids, and it is a question if it might not be as well 
to use dilute acids to neutralize the strong alkaline qualities of 
gums that go through certain kinds of coagulation. Some fac- 
tories also examine the coarser grades of gums, chemically, and 
give them a treatment to remove odor. As a rule, however, 
manufacturers rush them through the washing machines, sheet 
and dry them, and get them into the mixing mills as soon as 
possible. 

Drying. — The drying of rubber, according to earlier prac- 
tice, required a great deal of time. It was the boast of more 
than one rubber mill that no Para rubber was used by them until 
it had been dried for a year. The manufacturers of mechanical 
rubber goods were the first to break away from this tradition. 
In many cases they found, when there were rush orders on hand, 
that they must put on their mills gum that was practically just 
off the washer, and mix it, or else lose orders. Of course, they 
were forced to get most of the moisture out, or neutralize what 
was left, and they learned incidentally that they got a stronger 
compound with the green gum than with the "seasoned," whence 
the belief grew up that the months and years of drying were 
not necessary, as had before been supposed. In addition to this, 
some of them learned that long drying meant oxidation on the 
outside, or the turning of rubber into resin, which further in- 
creased their doubt of the wisdom of the slow-drying process. 

These thoughts once entertained, it was not long before 
various plans were introduced into the drying, for hastening the 
removal of the moisture. The simplest of these, of course, was 
artificial heat, and the presence of a fan for removing the 
moisture-laden atmosphere. Later developments have brought 
about a process, lasting only a few hours, for drying rubber 
very cheaply at quite a high heat, thereby giving it hot from the 
dryer to the man who runs the mixer, and doing away with the 
expensive process of breaking down. This latter idea is to some, 
of course, as revolutionary as was the first thought of quick 
drying, but that it is wholly in the line of progress is proved by 
the fact that it has now been used for a number of years by 
many manufacturers whose goods stand very high. 



MILLING— CALENDERING 353 

Milling. — The milling of crude rubber is simply putting on 
hot rolls the dry rubber which is found in a tough, intractable 
sheet, and running it until it gets to be a softened, homogeneous 
mass. The gum, when this is accomplished, is ready for mix- 
ing. These mixing rolls are run at different speeds and are 
called friction rolls, and the various adulterants and ingredients 
that are to be incorporated with the rubber are pressed into the 
softened gum by their revolution. 

No general rule can be laid down for mixing in all lines. 
An expert compounder knows that certain gums should be 
mixed on cool rolls, and others under considerable heat. His 
knowledge of specific compounds teaches him to hasten mixing 
in many cases, where another, without skill, would require very 
much more time to get the same result. In some cases the in- 
gredients are put in together, in others it is necessary to add 
them in definite order. Some have dissolved substances that 
would make the rubber stick to the rolls like glue unless they 
were put in at just the right time; others have so large a pro- 
portion of earthy matters that, unless the gum be humored, it 
apparently will not take them in, and so on. Each line of work 
and, in fact, each factory has its own special methods, and often 
one or more skilled mixers who can handle compounds that 
none of the others seem to be able to do anything with. 

Calendering. — The use of the calender is to sheet the 
goods so that they may be easily made into the desired forms. 
The simplest form of calender is a mixing mill with the key 
withdrawn that normally holds one roll in place, so that both 
run by even motion. This is used in many small factories where 
nothing but molded work is made. 

The modern sheeting calender is ordinarily a three-roll 
machine. It is sometimes made with four or more rolls, how- 
ever, and these rolls may be almost any size, the widest for 
rubber work being more than 80 inches. A considerable degree 
of skill is required for running the calender on a variety of 
stocks, nor can any general rules be laid down for calender work. 
This is proved by the value that is set upon good calender men, 
and by the difference that there is between the work of a good 
one and a poor one. There are as many different kinds of cal- 
enders as there are patterns of mixing mills. A sheet calender 



354 DIVISIONS OF RUBBER MANUFACTURE 

has smooth rolls, and is for running absolutely smooth goods. 
In shoe work there are engraved rolls, pebbled rolls, and sol- 
ing calenders engraved with knurled surface to produce the 
rough shoe sole. The carriage drill business has embossing cal- 
enders, and so on. A type of calender that is useful in most 
lines of work is known as the friction calender, the rolls in 
which run at uneven speeds and drive the gum deeply into or 
through the meshes of the fabric. 

Spreading. — Where india rubber is handled in solution 
there is used in place of the calender a spreading machine, known 
under the various names of "Yankee flyer," "English spreader," 
"doughing machine," etc. In this a sheet of rubber is spread 
on the cloth by being placed on an endless apron of the fabric, 
the apron running over the roll, against which hangs a heavy 
knife. A very thin coating of the rubber solution is constantly 
scraped off this surface, which then passes over hot drums or 
steam chests, evaporating the solvent. 

DIVISIONS OF RUBBER MANUFACTURE AND TYPICAL 
COMPOUNDS. 

The foremost European manufacturers of rubber goods, as 
a rule, make everything in the line of compounded rubber, hard 
or soft, and in addition often are producers of gutta-percha 
goods. In the United States, on the other hand, the tendency 
has been to specialize, and as a result the industry has divided 
itself naturally into the following general lines : mechanical 
rubber goods ; tires, pneumatic and solid ; molded work ; sun- 
dries, druggists', surgical, and stationers' ; dental and stamp rub- 
bers; surface clothing; carriage cloth; mackintoshes and proof- 
ing ; boots and shoes ; insulated wire ; hard rubber ; cements ; 
notions ; plasters ; and reclaimed rubber. 

The following brief description of the manipulation of rub- 
ber in these various lines is given because there are superinten- 
dents and managers who are experts in one line but who may 
be wholly unfamiliar with machinery and processes used in other 
lines. 

MECHANICAL RUBBER GOODS. 

This line of rubber manufacture, which is also known in 
Europe as technical rubber goods, embraces all the heavier com- 



COMPOUNDS FOR MECHANICAL GOODS 355 

binations of india rubber, metal, and fabric which are used in 
engineering and industrial lines. It covers, for example, belting, 
packings, hose, and special articles of almost endless variety and 
description. 

This portion of the rubber business has always been the 
pioneer in the production of new compounds, new processes, and 
better and heavier machinery. Its manufacturers always have 
welcomed new grades of rubber, have been the first to utilize 
those that were a drug on the market because of lack of knowl- 
edge as to their manipulation, were familiar with the uses of 
reclaimed rubber while yet other lines were simply considering 
its use, and with hundreds of compounds and cures and a broad 
knowledge of industrial achievement in all lines, they have often 
pointed the way for manufacturers in other lines to follow, to 
the betterment of their goods or their pockets. 

The mechanical rubber goods factory has the same general 
outfit in the way of machines for manipulating the crude gum 
as have the other lines. Their mixing mills, however, are often 
heavier, and their calenders run at higher speeds, while they 
have, in addition, enormously heavy hydraulic belt presses, huge 
vulcanizers, and scores of special machines designed for indi- 
vidual problems required for their line of work, or perhaps for 
a single factory alone. The kinds of vulcanization used in this 
work are (1) open steam heat, where the goods are buried in 
talc or wrapped in fabric; (2) dry heat, where they are confined 
by molds, and held in a steam press during the cure; or (3) 
where the goods, as in the case of belts, are molded between the 
platens of the press itself, while curing. Even in this line of 
work there are some concerns that do only special parts of it. 
For example, there are factories that make only certain types 
of packings which have a world-wide sale, and on which they 
are run continuously. 

COMPOUNDS FOR MECHANICAL GOODS. 

FRICTION FOR BELTING. COVER FOR BELTING. 

Central American 27.5 Coarse Para 20.00 

African small balls 12.0 Best shoe reclaim 45.00 

•p. , 00 ■,(■ r\ White substitute 12.50 

f aT u ytes i$-0 Barytes , 12.50 

Litharge 2^-5 Litharge 4.00 

Whiting 13.0 Whiting 4.00 

Sulphur 8.0 Sulphur 2.00 



356 DIVISIONS OF RUBBER MANUFACTURE 



compounds for mechanical goods. — {Continued) 



CHEAP WATER HOSE COVER. 

Coarse Para 12.50 

Best shoe reclaim' 50.00 

White substitute 7.00 

Barytes 15.00 

Litharge 2.50 

Fine rags 10.00 

Sulphur 1.25 

Cotton seed oil 1.75 

CHEAP WATER HOSE LINING. 

Coarse Para 5.5 

Assam 5.5 

African 5.5 

Best shoe reclaim 32.5 

White substitute 5.0 

Zinc oxide 8.0 

Barytes 8.0 

Litharge 8.0 

Whiting 8.0 

Blue lead 8.0 

Sulphur 3.0 

Cotton seed oil 3.0 

PERFORATED MATS OR PACKING. 

Coarse Para 7.75 

Assam 5.75 

Best shoe reclaim 29.00 

White substitute 7.75 

Black substitute 5 . 75 

Zinc oxide 5.75 

Barytes 13.50 

Whiting 7.75 

Sublimed lead 7.75 

Litharge 5.75 

Lime 0.50 

Sulphur 2.00 

Cotton seed oil 1 . 00 

MATTING. 

Borneo 7.50 

Shoe reclaim 44.50 

Whiting 18.50 

Sublimed lead 4.00 

Litharge 7.50 

Zinc oxide 9.00 

Soapstone 7.00 

Sulphur 2.00 

BILLIARD CUSHIONS. 

Fine Para 50.00 

Assam 21.00 

Sublimed lead 7.00 

Barytes 7.00 

Litharge 3.50 

Blue Lead 7.00 

Sulphur 4.50 



FIBROUS GASKETS. 

Fine Para 13.5 

Coarse Para 13.5 

Fine rags 13 .5 

Zinc oxide 13.5 

Barytes 10.0 

Litharge 5.0 

Soapstone 14.0 

Whiting 5.0 

Sulphur 3.0 

Blue lead 9.0 

RED SHEET PACKING. 

Coarse Para 10.00 

Pernambuco 10.00 

Gambier 10.00 

Red oxide 7.50 

Asbestine 55.00 

Sulphur 5 . 50 

Lime 1.00 

Coconut oil 1 .00 

BLACK SHEET PACKING. 

Lopori 22.0 

Mechanical goods reclaim .. 22.0 

Zinc oxide 17.0 

Sublimed lead 15 .0 

Asbestine 7.0 

Whiting 12.0 

Lampblack 3.0 

Lime 1.0 

Sulphur 1.0 

MACHINE ROLL. 

Fine Para 35.0 

African tongues 14.0 

Zinc oxide 14.0 

Litharge 14.0 

Paris white 18.0 

Sulphur 3.5 

Lampblack 1.0 

Lime 0.5 

WRINGER ROLL, INSIDE. 

African small ball 14.5 

Pontianak 14.5 

White vulcanized rubber dust 44.5 

Cotton fiber 14.5 

Sulphur 12.0 

WRINGER ROLL, OUTSIDE. 

Coarse Para 18.00 

Congo ball 7.00 

Zinc oxide 31.00 

Paris white 42.00 

Sulphur 1.75 

Lime 0.25 

WHITE TUBING, NO. I. 

Fine Para 21.5 

Coarse Para 21.5 



BOOTS AND SHOES 



357 



compounds for mechanical goods. — (Continued) 



WHITE TUBING, NO. I. (Cow.) 

Zinc oxide 51.5 

Sulphur , 4.5 

Lime 1.0 

WHITE TUBING, NO. II. 

Fine Para 21.50 

Coarse Para 21 .50 

Zinc oxide 25 . 50 

Whiting 20.00 

White substitute 5.75 

Sulphur 5.75 

CHEAP WHITE TUBING. 

Coarse Para 7.50 

Mozambique 7.50 

White substitute 9 . 00 

Zinc oxide 45.00 

Whiting 21.00 

Sulphur 3.00 

Lime 1.00 

Palm oil 6.00 

FIBER SOLE. 

Fine Para 30.0 

Reclaim 10.0 

Mineral rubber 5.0 

Cotton fiber 22.0 



FIBER SOLE. (Con.) 

Lithopone 

Calcined magnesia 

Sulphur 

WHITE SOLE. 

Coarse Para 

Ground waste rubber 

Zinc oxide 

Black substitute , 

Lime , 

Sulphur 

RED SOLE. 

Coarse Para 

Red inner tube reclaim.., 

Ground red soling 

Whiting , 

Red oxide of iron 

Calcined magnesia 

Sulphur , 

HEELS. 

Coarse Para 

Auto tire reclaim 

Ground waste rubber 

Mineral rubber 

Litharge 

Zinc oxide 

Whiting 

Sulphur 



27.0 
3.0 
3.0 

22.0 
43.5 
11.0 
11.0 
6.5 
6.0 

15.0 
40.0 
12.0 
14.0 
10.0 
3.0 
6.0 

10.0 

36.0 

20.0 

3.0 

2.0 

15.0 

12.0 

2.0 



BOOTS AND SHOES. 

The manufacture of rubber boots and shoes, although appar- 
ently a simple business, not only requires large capital, but is 
one that has often been overtaken by disaster. It is a matter of 
common knowledge that, given the same compounds, the same 
machinery, and the same skilled workmen, no two mills are able 
always to turn out exactly the same grades of goods. Quality 
is one ingredient that may or may not be added to the goods, no 
matter how honest the endeavor. That there are reasons for 
this, no one can doubt, and that the day will come when this 
branch of manufacture will be an exact science is probably true. 
That, however, will entail a definite knowledge of rubber from 
the moment it first sees the light as creamy liquid exuding from 
the tree, through every event in its life — in coagulation, transit, 
storage, factory manipulation, compounding, calendering, cur- 
ing, its death in the service of man, and its later resurrection 
in the process of reclaiming. The need for exact information 
regarding the ingredients added in the course of compounding 



358 DIVISIONS OF RUBBER MANUFACTURE 

and their relation to each other, mechanically and chemically, 
has been met by scientific study with marked improvement in 
quality of goods, machinery, and processes. 

In the complete rubber shoe plant there are found, for initial 
equipment, washing rolls, mixers, refining mills, and calenders 
such as most of the other lines employ. In addition, there are 
special calenders, with engraved rolls for shoe-upper work; 
others, also, with engraved rolls for soling; presses for molding 
boot heels, sole-cutting machines, and, of course, vulcanizers. As 
this class of goods is cured by what is known as the "dry heat" 
— that is, by being confined in dry, hot air for several hours — 
it will readily be seen that it is a radically different business 
from mechanical rubber goods, for instance. These dry heaters 
are simply large, ventilated rooms, fitted with steam pipes for 
heating, lined with tin, double walled to prevent radiation, into 
which hundreds of pairs of boots or shoes are run on skeleton 
cars, to undergo the process of vulcanization. The manufacture 
of rubber footwear, in brief, therefore, consists in washing, dry- 
ing, compounding and calendering the rubber and fabrics, the 
cutting of the calendered sheets into various shapes for cement- 
ing over lasts in the shapes desired, varnishing, and the dry- 
heat cure. 

The usual method of curing rubber boots and shoes consists 
in exposing them on racks in large, dry heaters where the tem- 
perature of the air is slowly raised by steam circulating in coils 
beneath the racks. Moisture and volatile products escape by 
natural ventilation through openings in the roof of the heater. 
The air, a poor conductor of heat, circulates slowly and with- 
out pressure. The working conditions are therefore not under 
positive control, and the time of vulcanization is long, usually 
from eight to ten hours. The fact that the goods, during vul- 
canizing, are not under pressure permits the formation of blisters 
wherever included air or moisture is present. The loss from 
this cause is sometimes very considerable, and difficult to rem- 
edy. Other defects of the dry heater system of curing are 
irregularity of cure, due to faulty circulation of the air; ex- 
cessive space required to handle the goods, because the cure is 
protracted unduly, and large cost of operation. Notwithstand- 
ing these defects and drawbacks, the dry heater has remained 



PRESSURE CURE OF FOOTWEAR 359 

the standard method for curing footwear since the earliest days 
of rubber manufacturing. 

The rubber boot and shoe industry is indebted to Hon. A. 
O. Bourn, of Bristol, Rhode Island, for the introduction of the 
first practical process for the pressure cure of footwear, which 
he developed in his own works at Providence, Rhode Island. 
Since his invention several others have been perfected, the work 
chiefly of American manufacturers. These methods of pressure 
cure mark the most important recent advance in the boot and 
shoe branch of the rubber industry, because they bring under 
control and obviate many of the troubles and inconveniences in- 
herent in the older process of curing footwear. 

Manufacturers are now able, by these inventions, to con- 
trol the vulcanizing process and produce better goods with fewer 
seconds. It is now possible to expel all air trapped between 
the plies in making, and under pressure to cure the shoe struc- 
ture compactly together. Pressure cure, by direct steam, also 
allows the use of tough wearing and oil resisting mechanical 
stocks, such, for example, as automobile tire tread compound. 

Other important advantages, due to these improved meth- 
ods, are great economy of space formerly devoted to heaters, 
and a very important saving of time in vulcanizing. These 
points materially increase the curing capacity of a factory, while 
the effectiveness of the process not only produces better goods, 
but permits the manufacture of boots and shoes of any desired 
color. This matter of freedom in color selection is an impor- 
tant one from a trade viewpoint, adding markedly to the va- 
riety and attractiveness of the goods. 

In the manufacture of mechanical goods the standard meth- 
ods of cure have commonly been pressure methods by steam 
heat, applied either in an atmosphere of steam or by steam- 
heated molds. The patented processes of pressure cure for 
boots and shoes are adaptations of these means to the special 
conditions of footwear manufacture by evolving certain general 
methods for removing trapped air and curing the goods com- 
pactly. 

These methods are in brief : 

1. Consolidation of structure of the goods by pressure of 
air or non-oxidizing gases and the application of their heat or 
that of steam. 



360 DIVISIONS OF RUBBER MANUFACTURE 



2. Removal by vacuum of entrapped air and vulcanization 
by pressure and heat applied by air, non-oxidizing, gases, or 
steam. 

3. Compression of the goods by inflation or otherwise, in 
a mold heated internally or externally by steam, for vulcani- 
zation. 

BOOT AND SHOE COMPOUNDS. 



SHOE UPPERS, HIGH GRADE. 

Fine Para 10.0 

Coarse Para 18.0 

Sulphur 1.0 

Litharge , 10.0 

Lampblack 1.0 

Coal tar 10.0 

Whiting 50.0 

SHOE UPPERS, MEDIUM GRADE. 

Fine Para 5.0 

Coarse Para 15.0 

Shoe reclaim 10.0 

Sulphur 1.0 

Litharge 8.0 

Lampblack 1.0 

Coal tar 24.0 

Whiting 36.0 

BOOT UPPERS, HIGH GRADE. 

Fine Para 30.0 

Coarse Para 15.0 

Sulphur 1.0 

Litharge 15.0 

Lampblack 2.0 

Coal tar 10.0 

Whiting , 27.0 

BOOT UPPERS, MEDIUM GRADE. 

Fine Para 9.0 

Coarse Para 25.0 

Shoe reclaim 10.0 

Sulphur 2.0 

Litharge 10.0 

Lampblack 2.0 

Whiting 30.0 

Coal tar 12.0 

SHOE SOLING, HIGH GRADE. 

Fine Para 10.0 

Central American 12.0 

Shoe reclaim 20.0 

Sulphur 1.0 

Litharge 10.0 

Lampblack 1.0 

Asphaltum 8.0 

Whiting 38.0 

SHOE SOLING, CHEAP GRADE. 

Coarse Para 10.0 

Shoe reclaim 46.0 

Sulphur 1.0 

Litharge 6.0 



SHOE SOLING, CHEAP GRADE. 

{Con.) 

Asphaltum 2.0 

Whiting 35.0 

BOOT SOLING, HIGH GRADE. 

Coarse Para 30.0 

Sulphur 1.0 

Litharge 15.0 

Lampblack 1.0 

Asphaltum 5.0 

Whiting 48.0 

BOOT HEELS, HIGH GRADE. 

Fine Para 5.0 

Coarse Para 15.0 

African grades 5.0 

Reclaim 20.0 

Sulphur 1.0 

Litharge 12.0 

Asphaltum 6.0 

Whiting 36.0 

BOOT HEELS, MEDIUM GRADE. 

African grade 10.0 

Reclaim 50.0 

Sulphur 1.0 

Litharge 8.0 

Asphaltum 6.0 

Whiting 25.0 

BLACK TENNIS SOLING. 

Fine Para 17.0 

Coarse Para 17.0 

Whiting 42.0 

Litharge 16.0 

Lampblack 2.0 

Sulphur 2.0 

Plaster of Paris 4.0 

BOOT AND SHOE FRICTION. 

Fine Para 15.0 

African grades 25 .0 

Sulphur 1.0 

Litharge 15 .0 

Whiting 44.0 

BOOT AND SHOE CEMENT. 

Fine Para 60.0 

Sulphur 2.0 

Litharge 38.0 

Dissolve in naphtha to consis- 
tency suitable for brush work. 



DRUGGISTS' AND STATIONERS' SUNDRIES 361 

RUBBER-SHOE VARNISH. 

Calcutta linseed oil is placed in an iron kettle over an an- 
thracite fire in a deep fireplace, to carry away the fumes. To 
the oil are added small proportions of litharge, sulphur and 
japan drier. The contents of the kettle are slowly boiled for 
some hours until well thickened. The liquid requires constant 
attention and frequent stirring to prevent ignition or rais- 
ing over the top of the kettle. When judged sufficiently boiled, 
the kettle is removed out of doors and when well cooled the 
contents are thinned for use to about 50 degrees Baume with 
turpentine and naphtha. Care must be exercised that the addi- 
tion of these volatile liquids be not made under conditions per- 
mitting their vapors to find their way to the fire in the varnish 
house, or disastrous consequences will result. A simple method 
of preventing this is to place sand bags at the bottoms of the 
doors of the varnish boiling room. 

DRUGGISTS', STATIONERS' AND SURGICAL SUNDRIES. 

This part of the rubber business entails more skillful 
manipulation and more finesse in manufacture than almost any 
other line. An atomizer bulb, for example, must be graceful 
in shape, with delicately smooth surface, of good color, and 
either of the non-blooming variety or so near it that the sul- 
phurous efflorescence will be so slight as to pass unnoticed, 
while in mechanical goods a length of garden hose may be of 
any color, may bloom until crusted with sulphur crystals, but 
if it "stands up to work," it is the best, and is beautiful in the 
eyes of the trade. 

The question of colored rubber is one that has interested 
this branch of the business from its inception. In none other 
is so much white rubber made and, incidentally, none others 
get such good effects. This insistence by customers on white 
goods and by physicians on black, containing no trace of lead, 
has entailed a deal of trouble upon this trade, for the manu- 
facturers until recently could not go into the open market and 
buy a high grade of white recovered rubber, while of black 
there is ever an ample supply, and for black goods to suit the 
physician the manufacturer is forced to substitute a dry, bulky 



362 DIVISIONS OF RUBBER MANUFACTURE 

vegetable black for oxide of lead or white lead, and then not 
get as good a result. 

The machinery used is very similar to the equipment of a 
mechanical goods factory, but the scale is smaller. Washers, 
grinders, calenders, tubing machines, steam vulcanizers, and 
small steam presses are the machines used. Special machines 
are employed in certain parts of the work, but their use is lim- 
ited to a few factories. 

The feature in this trade which stands out most distinctly 
from other rubber lines is, perhaps, the manufacture of hollow 
work, as atomizers, syringes, breast-pumps, and a host of 
other balls and bulbs. The parts for these are cut from sheets 
of compounded rubber, cemented together at the edges, inflated 
to the general shape of the mold and cured in open steam heat. 
In order that the ball may fill the mold perfectly during the 
cure, a few drops of water or a little ammonia are put inside 
of it which, vaporizing under the heat, develops pressure enough 
to perfectly shape it and add to its outer surface the finish 
found on the inner surface of the mold. 

The difficulties that manufacturers in this line experience 
in making perfect goods are legion, as they are in other lines. 
They are added to by the fact that the trade, as already indi- 
cated, demands articles of beauty from a gum that was de- 
signed for utility solely. A trace of black in a white compound 
may spoil hundreds of dollars' worth of goods, nor can such 
trace be rubbed off, scoured out, or eradicated, after vulcani- 
zation. Hence, white, black, red and other colors must be 
mixed on separate mills, and the trimmings and scraps kept 
sedulously apart. 

Pure gum — that is, rubber compounded only with sulphur 
or some other vulcanizing agent — is also largely produced in 
this line. For example, it makes what is known as dental dam, 
the pure sheet used by dentists. This is generally a sulphur 
compound, cured in open steam. Certain manufacturers, how- 
ever, practice the vapor cure with good success in making these 
goods. This cure gives a beautiful finish, but if not done with 
great skill it may be disastrous to both the workman and the 
goods. 



DRUGGISTS' SUNDRIES, ETC., COMPOUNDS 363 

Dental dam, surgical bandages, and stationers' bands repre- 
sent the highest priced and least compounded goods, while 
stopples, erasive rubber, and common tubing represent the other 
extreme. Between the two is a latitude that allows a variety of 
combinations that no man can number. 

COMPOUNDS FOR DRUGGISTS'", STATIONERS'" AND SURGICAL 
SUNDRIES. 



WHITE BULBS. 

Fine Para 

Zinc oxide 

Whiting 

Ground white scrap 
Sulphur 

BLACK BULBS. 

Fine Para 

Zinc oxide 

Whiting 

Sublimed lead 

Lampblack 

Sulphur 



36.0 
36.0 
11.0 
11.0 
6.0 

43.0 
22.0 
10.0 
13.0 
4.0 
8.0 

10.5 
42.5 
4.0 
6.5 
5.5 
3.0 
25.0 
3.0 



WHITE STOPPERS. 

Coarse Para 

Zinc oxide 

Sulphur 

White substitute 

Asbestine 

Cotton seed oil 

Wringer roll dust 

Lime 

BLACK STOPPERS. 

Pernambuco 30.0 

Sublimed lead 5.0 

Litharge 5.0 

Sulphur 4.0 

Lime 10.0 

Lampblack -. 4.0 

Ground waste rubber 42.0 

AIR CUSHIONS. 

Fine Para 50.0 

Zinc oxide 36.0 

Whiting 12.5 

Sulphur 1.5 

ELASTIC BANDS (GRAY) 

Fine Para 94.0 

Sulphur 6.0 

CATHETERS. 

Fine Para 43.0 

Paris white 30.0 

Golden antimony 12.5 

Substitute 3.5 

Whiting 10.0 

Vermilion 1.0 



TAN WATER BOTTLE. 

Fine Para 31 .0 

Whiting 48.0 

White substitute 10.0 

Infusorial earth 2.0 

Lime 0.5 

Golden antimony 8.5 

WHITE WATER BOTTLE. 

Lagos 20.00 

Cameta 5 . 00 

Zinc oxide 42 . 50 

Asbestine 8.50 

Sulphur 2.00 

Substitute 5.00 

Whiting 16.75 

Lime . 25 

MAROON WATER BOTTLE. 

Lagos 20.00 

Cameta 5.00 

Zinc oxide 42.50 

Asbestine 8.50 

Maroon lake 2.00 

Sulphur 2.00 

Substitute 5.00 

Whiting 14.75 

Lime . 25 

PENCIL ERASER. 

Fine Para 

Madagascar , 

Zinc oxide 

Whiting 

Pumice 

Sulphur 

INK ERASER. 

Fine Para 

Madagascar 

Zinc oxide 

Pumice 

Ground glass 

Sulphur 

SPONGE RUBBER, NO. 

Coarse Para 

White substitute 

Sulphur , 

Whiting 

Alum 



17.5 
17.5 
35.0 
17.5 
10.0 
2.5 

18.5 

18.5 

37.0 

14.5 

8.0 

3.5 

[. 

40.0 
30.0 
5.0 
10.0 
15.0 



364 DIVISIONS OF RUBBER MANUFACTURE 

COMPOUNDS FOR DRUGGISTS', STATIONERS' AND SURGICAL 

sundries. — ( Continued ) 

SPONGE RUBBER, NO. II. NON-BLOOMING BLACK. 

S^* SeP wV; ™'X Fine Para 35.0 

White substitute 10.0 

Whiting 50.0 Litharge 18.0 

Sulphur 2.0 Whiting 36.0 

Ceresin 3.0 T ,, , on 

Pine oil 2 .Lampblack Z.v 

Ammonium carbonate 8.0 Lead hyposulphite 9.0 

MACKINTOSHES, PROOFING AND CARRIAGE CLOTH. 

This business may be handled, in a measure, as the 
mechanical goods business is; that is, the gums may be mixed 
by heat on ordinary mixers, and then spread by calenders on 
the fabrics which give the articles their strength. This is the 
manner in which rubber surface clothing is run. The machin- 
ery is simple, since, in clothing, the parts are cemented together 
and cured in dry heat. In carriage cloths, after calendering, 
the goods are grained on embossing rolls, varnished, and run 
into a dry heat. 

The mackintosh and proofing business, however, is some- 
what a departure from this. Here the gum, after mixing dry, 
is usually put in churns with a cheap solvent and reduced to a 
solution. It is then applied to the cloth with a knife spreader. 

For double-texture work, a simple doubling machine brings 
two surfaces together. A portion of the business that has di- 
vided itself from the rest is what is known as proofing for the 
trade. Here manufacturers simply coat the cloth and sell it to 
others, who make it up into garments, or anything in fabric or 
rubber for which there may be a call. The mackintosh manu- 
facturer today is not only familiar with a great variety of 
rubber gums and ingredients used in compounding, but is also 
an expert in fabrics, as his business is really closely akin to the 
tailoring business. 

CLOTHING AND CARRIAGE CLOTH COMPOUNDS. 

DULL FINISH CLOTHING. DULL FINISH HEAVY COATS. 

Fine Para 47.00 Fine Para 10.0 

Reclaim 16.00 Reclaim 68.0 

Whiting 16.00 Paris white 10.0 

Litharge 10.50 Lampblack 3.0 

Coal tar 5.50 Litharge 5.0 

Sulphur 2.50 Sulphur 0.5 

Palm oil 1 .25 Black substitute 2.0 

Rosin 1.25 Coal tar 1.5 



CLOTHING COMPOUNDS, ETC. 



365 



CLOTHING AND CARRIAGE CLOTH 
WHITE SURFACE CLOTHING. 

Fine Para 24.0 

White reclaimed 30.0 

Whiting 20.0 

Zinc oxide 20.0 

Calcined magnesia 5.0 

Sulphur 1.0 

DOUBLE TEXTURE. 

Fine Para 80.0 

Paris white 8.0 

Litharge 9.0 

Zinc oxide 1.0 

Sulphur 2.0 

CHEAP DOUBLE TEXTURE. 

Lump African flake 2.00 

Accra buttons 3 .00 

Black substitute 28.00 

Cheap shoe reclaim 23.50 

Gilders' whiting 26.25 

Litharge 9.25 

Coal tar 1.00 

Sulphur 1.00 

Pontianak 3.75 

Calcined magnesia 2.00 

Rosin 0.25 

GOSSAMER FINISH. 

Fine Para 53.0 

Paris white 25.0 

Lampblack 7.0 

Shellac 14.0 

Sulphur 1.0 

TRANSPARENT GOSSAMER, 

Fine Para 37.0 

Central American 37.0 

Shellac 12.5 

Substitute 12.0 

Sulphur 1.5 

SINGLE TEXTURE CLOTHING. 

Fine Para 57.50 

Zinc oxide 30.00 

Litharge 8.50 

Lampblack 3.00 

Sulphur 0.75 

Palm oil 0.25 

CEMENT FOR HEAVY COATS. 

Fine Para 46.0 

Whiting 31.0 

Litharge 12.0 

Lampblack 8.0 

Sulphur 1.0 

Rosin 1.0 

Coal tar 1.0 

CEMENT FOR COATS. 

Central American 16.0 

African flake 16.0 



compounds. — (Continued) 

CEMENT FOR COATS. (Con.) 

Whiting 30.0 

Litharge 3.5 

Reclaim 33.0 

Sulphur 1.5 

VULCANIZED GOSSAMER. 

Fine Para 20.0 

Whiting 62.0 

Lampblack 8.0 

Litharge 8.0 

Coal tar 1.5 

Sulphur 0.5 

CHEAP GOSSAMER. 

Rubber 5.00 

Reclaim 62.00 

Whiting 17.00 

Coal tar 3.50 

Lampblack 1 .75 

Litharge 10.00 

Sulphur 0.75 

PROOFING. 

African flake 2.0 

Accra buttons 10.0 

Shoe reclaim 40.0 

White substitute 6.0 

Litharge 5.0 

Calcined magnesia 5.0 

Paris white 26.0 

Sulphur 1.0 

Zinc oxide 3.0 

Palm oil 2.0 

CHEAP PROOFING. 

Reclaim 33.0 

Pontianak 16.0 

Whiting 28.0 

Black substitute 10.0 

Litharge 10.0 

Sulphur 1.5 

Coal tar 1.5 

CARRIAGE CLOTH, NO. I. 

Coarse Para 7.00 

Reclaim 71 . 50 

Whiting 14.00 

Litharge 4.00 

Lampblack 2.50 

Sulphur 0.25 

Coal tar 0.75 

CARRIAGE CLOTH, NO. II. 

Coarse Para 7 . 00 

Substitute 3 . 50 

Reclaim , 62 . 50 

Paris white 10.50 

Litharge 7.00 

Lampblack 4.25 

Tar ,. 2.25 

Mineral rubber 2.25 

Sulphur 0.75 



366 DIVISIONS OF RUBBER MANUFACTURE 

TIRES. 

Although the tire business seemed at first to be a natural 
part of the mechanical rubber goods business, it really proved 
itself, later, to be a business wholly distinct from it. Even the 
large manufacturers of mechanical goods who began tire mak- 
ing on a considerable scale, keep this part of their business 
distinct from other branches as a rule, running it as an 
entirely separate department. A large business is done in pneu- 
matic tires for bicycles and motor-cycles, but it is much sur- 
passed by the production of pneumatic automobile tires. The 
knowledge gained through the manufacture of pneumatic 
bicycle tires (which, by the way, was one of the hardest prob- 
lems that the rubber trade ever solved) has proved wonder- 
fully effective in developing the skill necessary to make this 
heavier and more important article. This tire, like the bicycle 
tire, is built up of frictioned duck, with an outer coating of 
high-grade rubber carefully vulcanized. While a variety of 
compounds is used in its make-up, it is true that no manufac- 
turer is able to sell a very low grade of goods, even of unguar- 
anteed quality, because the life of the tire is so important, and 
the purchaser so desirous for a good article. Cheapening to 
any great extent is not feasible, particularly in tires sold under 
mileage guarantee. An adjunct of this business is the manu- 
facture of inner tubes, which has assumed very large pro- 
portions. 

The general machinery used in making tires is the same 
that is used in the work of preparing rubber in other lines. 
There are two general classes of tires manufactured, however: 
Those that are molded, and those that are made in such a way 
that they can be wrapped for the process of vulcanization. 
Wrapped goods, of course, are cured in an open heat. In the 
one case the tires are cured in presses, sometimes in nests of 
molds, and sometimes in vulcanizers. Various ingenious and 
valuable processes and special machines have been invented, 
and are now in use in this line. An industry that has grown 
up in connection with the tire business, and has increased the 
practical knowledge of the uses of rubber wonderfully, is that 
of tire repairing, which is carried on in many places and to an 
important extent outside of the rubber factories proper. 



TIRE COMPOUNDS 



367 



A part of the tire business that is of great interest is the 
making of the solid or cushion molded tire used on light 
vehicles. Formerly a very large business was done in this, the 
work being a simple process of mixing the prepared compound, 
forcing it into shape through a tubing machine, and molding. 
Of increasing importance is the business of producing heavy 
solid tires for motor trucks, omnibuses, fire engines, and freight 
wagons. These are made either by the tubing machine or by 
building up at the calender from sheeted stock. Many rubber 
manufacturers have specialized in this line and their yearly 
product is very great. 

TIRE COMPOUNDS. 



AUTO TIRE TREAD BLACK. 

Fine Para 45.0 

Zinc oxide 25 .0 

Carbon black 10.0 

Mineral rubber 6.0 

Aluminum flake 11.0 

Sulphur 3.0 

AUTO TIRE TREAD — WHITE. 

Fine Para 44.0 

Zinc oxide 47 . 

Lime 1.0 

Sulphur 3.0 

Aluminum flake 5.0 

AUTO TIRE FRICTION. 

Para 30.0 

Caucho 20.0 

Upper Congo 20.0 

Uncured friction reclaim 10.0 

Zinc oxidq 12.5 

Lime 0.5 

Sulphur 7.0 

RED AUTO INNER TUBE. 

Fine Para 75.0 

Golden antimony 20.0 

Zinc oxide 4.0 

Calcined magnesia 1.0 

GRAY AUTO INNER TUBE. 

Fine Para 92 . 5 

Sulphur 7.5 

AUTOMOBILE TIRE-REPAIR 
COMPOUND. 

Fine Para 28.0 

Reclaim 26.0 

Calcined magnesia 8.0 

Sulphur 12.0 

Mineral rubber 3.0 

Litharge 14.0 

Infusorial earth 6.0 

Lime 3.0 



INNER TUBE REPAIR 
COMPOUND. 

Fine Para 34.0 

Upper Congo 34.0 

Sulphur 6.5 

Black substitute 13.5 

Infusorial earth 10.0 

Calcined magnesia 1.0 

Mineral rubber 1.0 

INNER TUBE SPLICING CEMENT. 

Fine Para 55.0 

Sulphur 14.0 

Litharge 14.0 

Zinc oxide 14.0 

Lime 3.0 

BEAD CEMENT. 

African ball 26.0 

White substitute 4.0 

Litharge 40.0 

Sublimed lead 3.0 

Asbestos 9.0 

Whiting 8.0 

Lime 2.0 

Sulphur 8.0 

BICYCLE TIRE-RIM CEMENT. 

Gutta-percha 5 pounds 

Asphalt 10 pounds 

Melt together and apply hot. 

BICYCLE TIRE COVER. 

Fine Para 64.0 

Infusorial earth 12.0 

Blue lead 8.0 

Whiting 5.5 

White substitute 5.0 

Sulphur 5.5 



368 DIVISIONS OF RUBBER MANUFACTURE 
tire compounds. — {Continued) 

BICYCLE TIRE INNER TUBE. SOLID CARRIAGE TIRE. 

Fine Para 80.0 Coarse Para 5.0 

Zinc oxide 9.5 Upper Congo 12.0 

Blue lead 1.5 Zinc oxide 24.0 

Litharge 1.5 Sublimed lead 10.0 

Paris white 3.0 Litharge 10.0 

Sulphur 4.0 Ground solid tire 17.0 

Lime 0.5 Best reclaim 19.5 

Sulphur 2.5 

BICYCLE TIRE FRICTION. 

Fine Para 32.0 CAB TIRE. 

Accra 25.0 p 43 75 

Cameroons 7.0 ~. ara ".*,' 07'cn 



Litharge 8.0 

Lime 2.5 



Zinc oxide 27 . 50 

Infusorial earth 23.00 



whiting':::::::::::::::::: is:o sulphur 4.50 

Sulphur 7.5 Litharge 1.25 

BABY CARRIAGE TIRE. SOLID TRUCK TIRE. 

Congo 10.5 Fine Para 40.0 

Pontianak 8.5 Auto tire reclaim 8.0 

Floating reclaim 10.5 Zinc oxide 20.0 

Cheap reclaim 10.5 Litharge 5.0 

Substitute 8.5 Sulphur 4.0 

Whiting 26.0 Calcined magnesia 5.0 

Barytes 21 .0 Mineral rubber 3.0 

Sulphur 4.5 Asbestine 15.0 

INSULATED WIRE. 

The manufacture of insulated wire, either with india rubber 
compound or gutta-percha insulation, is a line that is more dis- 
tinctly apart from other portions of the rubber business than 
almost any other. For gutta-percha, the general machinery 
used is described in the chapter on that gum. Where india rub- 
ber is used, the crude gum is treated in the same way as in 
mechanical goods. It may be forced over the wires by tubing 
machines, or welded together in strips that are run between 
grooved rolls. 

Braiding machines are also a part of the outfit for weav- 
ing the protective covering, and the wire is usually wound on 
huge drums and vulcanized in open steam heat or in pans under 
water in open steam. Polishing machines, testing machines, 
and various mechanical contrivances are, also, a part of this 
equipment. The line of compounds used is one adapted almost 
wholly to this industry, and embraces a great variety of in- 
gredients and gums that are treated specifically, under their spe- 
cial heads, elsewhere in this book. 



INSULATION COMPOUNDS 



369 



WHITE CORE. 

Fine Para 

Magnesia 

Litharge 

Whiting 

BLACK CORE. 

Fine Para 

Magnesia 

Lampblack 

Litharge 

Whiting 

RED ANTIMONY CORE 

Coarse Para 

Soapstone 

Golden antimony 

White substitute 



INSULATION COMPOUNDS. 

WHITE ELECTRIC TAPE. 



40.0 
26.0 
20.0 
14.0 

26.0 

25.0 

4.0 

20.0 
25.0 

36.0 

50.0 

10.0 

4.0 

RED CORE. 

Coarse Para 20.0 

Zinc oxide 15.0 

Iron oxide 5.0 

White substitute 10.0 

Whiting , 50.0 

UNVULCANIZING INSULATION. 

Coarse Para 33 . 3 

Balata 33.3 

Reclaim (not devulcanized) 33.4 

GRAPHITE INSULATION. 

Coarse Para 45 . 5 

Graphite 45.5 

Sulphur 9.0 

HARD WIRE COVERING. 

Madagascar 14.5 

Balata 57.0 

Sulphur 28.5 

SOFT COVERING, NO. I. 

Madagascar 57 .0 

Balata 28.5 

Sulphur 14.5 

SOFT COVERING, NO. II. 

Central American 5.5 

Reclaim 64.5 

Litharge 4.0 

Silica 25.0 

Sulphur 1.0 



African soft ball 15.0 

Cameroons 20 .0 

African flake 10.0 

Whiting 15.0 

Zinc oxide 30.0 

Sulphur 5.0 

Rosin 5.0 

WHITE ELECTRIC TAPE. 

Borneo 9.0 

African flake 22.0 

Balsam fir 2.0 

Whiting 55.0 

Zinc oxide 12.0 

BLACK ELECTRIC TAPE. 

Assam 12.0 

African flake 12 .0 

Pontianak 14.0 

Barytes _ 32.0 

Zinc oxide 25.0 

Lampblack 4.0 

Turpentine, crude 1.0 

FRICTION TAPE, NO. I. 

Fine Para 13.0 

African small ball 13.0 

African flake 3.0 

Best shoe reclaim 16.0 

Zinc oxide 8.0 

Barytes 13.0 

Litharge 13.0 

Whiting 13.0 

Sublimed lead 5.0 

Sulphur 3.0 

FRICTION TAPE, NO. II. 

Coarse Para 15.0 

African small ball 15.0 

African flake 1.5 

Zinc oxide 33.0 

Whiting 30.0 

Sulphur 2.5 

Cotton seed oil 3.0 



MOLDED GOODS MANUFACTURE. 

A part of the rubber business that belongs either to the 

mechanical or to the druggists' sundries line has, during the 

past few years, detached itself from the rest, so that today 

many large factories are run simply in producing small mold 



370 DIVISIONS OF RUBBER MANUFACTURE 



work. They have the usual equipment of rubber machinery, 
special appliances for filling and emptying molds, and the usual 
aggregation of hard and soft metal molds that run into thou- 
sands of dollars in a short time. The extent to which this busi- 
ness is carried may be imagined when it is known that one 
company runs 300 presses on this work, and many have from 20 
to 50 in constant service. When it is remembered that very rarely 
are two compounds exactly alike, it will be seen that, in this 
line also, the expert compounder has a wide field for thought 
and experiment. 

COMPOUNDS FOR MOLDED GOODS. 



TOUGH MEDIUM HARD VALVE. 

Fine Para 32. 50 

Barytes 19.25 

Litharge 9.75 

Plumbago 8.00 

Wlhiting 16.00 

Blue lead 6.50 

Sulphur 8.00 

SOFT PUMP VALVE. 

Fine Para 17.0 

Coarse Para 26.0 

Barytes 14.0 

Litharge 13.0 

Whiting 13.0 

Blue lead 13.0 

Lampblack 0.5 

Sulphur 3.5 

SMALL ARTICLES, NO. I. 

Coarse Para 22.00 

Blue lead 13.00 

Whiting 32.50 

Infusorial earth 22.00 

Litharge 4.25 

Sulphur 4.25 

Lime 2.00 

SMALL ARTICLES, NO. II. 

Penang 34.0 

Black substitute 7.0 

Zinc oxide 30.0 

Sublimed lead 13.0 

Litharge 13.0 

Sulphur 3.0 

SMALL ARTICLES, NO. III. 

Coarse Para 9.0 

Reclaim 55.0 

Barytes 22.0 

Litharge 4.5 

Blue lead 2.0 



SMALL ARTICLES, NO. III. — 

(Con.) 

Lime 3.0 

Sulphur 3.0 

Cotton seed oil 1.5 

SPRINGS. 

Coarse Para 12.0 

African 16.0 

Ground rubber waste 27.0 

Litharge 13.5 

Whiting 27.0 

Lime 0.5 

Sulphur 4.0 

RED SOFT PUMP VALVE. 

Fine Para 39.5 

Coarse Para 39. 5 

Antimony golden sulphide . . 19.0 
Sulphur 2.0 

MEDIUM PUMP VALVE. 

Fine Para 8.0 

Coarse Para 8.0 

African thimbles 10.5 

Barytes 16.0 

Litharge 10.5 

Whiting 13.0 

Soapstone 13.0 

Blue lead 18.5 

Sulphur 2.5 

LARGE ARTICLES. 

Lopori 10.00 

Black substitute 4. 00 

Ground solid tires 65.00 

Barytes 12.00 

Litharge 4.00 

Lime 1.75 

Sulphur 2.00 

Palm oil 1.25 



HARD RUBBER COMPOUNDS 371 

compounds for molded goods. — (Continued) 

BUMPERS. HOOF PADS. 

L°P° ri ••••••; 9.0 Quayule 10.5 

Black substitute 4.0 

White substitute 5.0 Reclaim 10.5 

Ground solid tires 16.0 Ground cured waste 42.0 

Shoe reclaim oo.U 

Infusorial earth 2.0 Zinc oxide 16.0 

Litharge 4.0 Whiting 16.0 

Lime 0.5 

Sulphur 3.0 Lime I- 

Petrolatum 0.5 Sulphur 4.0 

HARD RUBBER. 

In spite of the hundreds of substitutes for vulcanite, or 
hard rubber, that have been produced, the demand has in no 
way fallen off, and mills are running full today on the produc- 
tion of this semi-metal. The old-fashioned compound, consist- 
ing of 2 pounds of india rubber to 1 pound of sulphur, is still 
in Use in certain goods. Modern progress and chemical knowl- 
edge have, however, added a great many compounds for spe- 
cific uses, so that almost any degree of quality, or hardness, or 
price, is now furnished on call. 

The business, primarily, is a simple one, the hard rubber 
machinery being like that used in other lines. In the manipu- 
lation of the gum for vulcanization, and in its finish, however, 
special machines are necessary. The finishing machines are 
lathes, saws, buffers, etc., somewhat similar to what might be 
used for turning hard wood. The mechanical factories often 
do a little in hard rubber in the line of valves, and the drug- 
gists' sundries mills often make their own syringe fittings, but 
the bulk of the business in America is done by mills that make 
only vulcanite the year around. 

HARD RUBBER COMPOUNDS. 
SMALL MOLD WORK. BATTERY BOX. 

Coarse Para 38.0 Coarse Para 28.0 

Madagascar 16.0 g ala f a V •;.;•; Jj'X 

Hard rubber dust 32.5 Black substitute 14.0 

Blue lead 11.0 Asbestine 14.0 

Palm oil 2.5 Su lphur . . 14.0 

Hard rubber dust 14.0 

Cotton seed oil 2.0 

SHEETS. 

Fine Para 25.00 Fine Para 27.50 

Substitute 8.00 Pinky Madagascar 27.50 

Zinc oxide 60.00 Sulphur 41.00 

Sulphur 4.25 Lime 2.75 

Palm oil 2.75 Beeswax 1.25 



FINE TUBING. 



372 DIVISIONS OF RUBBER MANUFACTURE 



hard rubber compounds. — {Continued) 

RED MOLDED. (Con.) 

Vermilion 14.0 

China clay 7.0 

Sulphur 18.0 

Palm oil 



RODS. 

Pinky Madagascar , 13 .00 

Congo ball 8.00 

Borneo 5.25 

Hard rubber dust 44.00 

Sulphur 23.50 

Cotton seed oil 4.00 

Beeswax . 75 

Lime 1 . 50 

SYRINGE PIPES. 

Fine Para 53.5 

Sulphur 28.5 

Hard rubber dust 18.0 

RED MOLDED. 

Fine Para 53 . 

Red oxide 7.0 



1.0 

SEMI-HARD. 

Fine Para 34.0 

Sublimed lead 17.0 

Zinc oxide 17.0 

Litharge 17.0 

Lampblack 11.5 

Sulphur 3.5 

COMBS. 

Fine Para 53.0 

Sulphur 47.0 



CEMENTS. 
Many rubber factories are run wholly on this line of work, 
the gums being mixed as in a general rubber business, put into 
solution in churns, and sold by the barrel for an infinite variety 
of purposes. Hundreds of different formulas are in use for 
cements intended for general and specific purposes. The 
leather shoe business, for instance, calls for a dozen or more 
special cements. The bicycle business has need for a great 
many grades of what are known as tire cements. Stickiness, 
waterproof qualities, durability, and cheapness in their goods 
are sought by all cement manufacturers, and, in order to secure 
these qualities, they demand skill in compounding in no way 
inferior to that shown in other lines of rubber work. 

CEMENT COMPOUNDS. 



PURE-GUM CEMENT. 

Fine Para dissolved in benzol or 
naphtha. 

WHITE (CURING). 

Fine Para 20 pounds 

Zinc oxide 12 pounds 

Sulphur 2 pounds 

Naphtha 25 gallons 

YELLOW ( CURING) . 

Fine Para 20 pounds 

Litharge 8 pounds 

Zinc oxide 8 pounds 

Sulphur 2 pounds 

Naphtha 25 gallons 



LEATHER SOLE CHANNEL, 
NO. I. 

Fine Para (washed) . . 30 pounds 

Rosin 5 pounds 

Naphtha 40 gallons 

LEATHER SOLE CHANNEL, 

NO. II. 

Fine Para (washed) . . 10 pounds 

Rosin 5 pounds 

Naphtha 40 gallons 

HARD-RUBBER CEMENT. 

Fine Para 30 pounds 

Sulphur 10 pounds 

Naphtha 12 gallons 



DENTAL AND STAMP GUM COMPOUNDS 373 



cement compounds. — {Continued) 

davy's universal. 

Gutta-percha. 
Common pitch. 

Equal parts of each melted to- 
gether. 



LEATHER WELTING. 

Fine Para 10 pounds 

Sulphur S ounces 

Naphtha 10 gallons 

LEATHER SOLE-LAYING. 
Lagos buttons or strips 10 pounds 

Pontianak 5 pounds 

Naphtha 20 gallons 

LEATHER BELTING, NO. I. 

Carbon bisulphide 20 pounds 

Oil of turpentine 2 pounds 

Gutta-percha sufficient to form a 

paste. 
LEATHER BELTING, NO. II. 

Caoutchouc 6 pounds 

Shellac 4 pounds 

Carbon bisulphide 40 pounds 

Turpentine 4 pounds 



FINE DIPPED WORK. 

Fine Para 2 pounds 

Carbon bisulphide 60 pounds 

Absolute alcohol 4 pounds 

MARINE GLUE, FRENCH. 

Dissolve 10 pounds caoutchouc 
in naphtha and add 20 pounds 
shellac. Melt until mixed and 
pour while hot on metal plates to 
cool. 



DENTAL AND STAMP GUM. 
The manufacture of unvulcanized gums for the use of 
dentists and rubber-stamp manufacturers is an industry apart 
from other lines, and one that has assumed large proportions. 
The rubber is compounded and sold by the manufacturer, and 
cured and finished by the dentist or rubber-stamp manufac- 
turer. In stamp work the rubber is compounded for soft rubber 
and many hundreds of tons are sold during the year, while, 
of course, the dental rubber is so mixed that under the cure 
it becomes vulcanite of the color desired. The machinery for 
this work consists chiefly of washers, mixers, and calenders. 

DENTAL AND STAMP GUM COMPOUNDS. 



DENTAL — LIGHT PINK. 

Fine Para 16.0 

Lithopone (green seal) 56.0 

Lac sulphur 6.0 

Lime 2.0 

Pale vermilion 20.0 

Ultramarine blue Trace 

DENTAL BLACK PALATE. 

Fine Para 77.0 

Lac sulphur 15.0 

Lampblack 4.0 

Lime 4.0 

DENTAL — RED PALATE. 

Fine Para 62.5 

Lac sulphur 12.5 

Dark vermilion 22.0 

Lime 3.0 



DENTAL BLACK WEIGHTED. 

Fine Para 20.5 

Lac sulphur 15.5 

Lime 1.0 

Pure tin foil 61 . 5 

Raw linseed oil 1.5 



STAMP GUM, NO. I. 

Fine Para 44.0 

Whiting 9.0 

Zinc oxide 11.0 

Talc 9.0 

Litharge 18.0 

Lime 1.0 

Mineral rubber 2.0 

Sulphur 6.0 



374 DIVISIONS OF RUBBER MANUFACTURE 



STAMP GUM, NO. III. 

Fine Para 17.0 

Borneo 34.0 

Litharge 8.5 

White Lead 8.5 

Whiting 8.5 

Lime 6.5 

Barytes 8.5 

Sulphur 8.5 



dental and stamp gum compounds. — {Continued) 

STAMP GUM, NO. II. 

Fine Para 20.0 

Coarse Para 20.0 

Whiting 20.0 

Zinc oxide 27 . 

Litharge 10.0 

Sulphur - 3.0 

NOTIONS. 
This department of the rubber business, the importance 
of which is not generally appreciated, is that which takes in 
such work as waterproof dress bindings, dress shields, chil- 
dren's aprons, diapers, etc. Several large factories manufac- 
ture these goods, mixing their rubber by the usual processes, 
coating it on calenders, and having special machines for form- 
ing and curing the goods in their special shapes. In the manu- 
facture of dress shields the vapor cure is often practiced very 
successfully. The rubber manufacturers of this class are not 
by any means inexpert compounders. They have also, perhaps, 
gone as far as any in deodorizing rubber goods so that the 
smell of the gum or any compounding ingredients is wholly 
done away with. 

notion-trade compounds. 



DRESS SHIELDS. 

Fine Para 45.0 

Zinc oxide 25.0 

White substitute 14.5 

Litharge 12.5 

Sulphur 3.0 

BLUE SHEETING VAPOR 

CURE. 

Fine Para 56 . 5 

Zinc oxide 38. 

Ultramarine blue 5.5 

WHITE SHEETING VAPOR 

CURE. 

Fine Para 60.0 

Zinc oxide 40.0 

NURSERY SHEETING. 

Fine Para 39.0 

Zinc oxide 29 . 

Whiting 29.0 

Sulphur 2.5 

Palm oil 0.5 



WHITE BATHING CAP. 

Fine Para 75.0 

Zinc oxide 20.0 

Sulphur 5.0 

Calcined magnesia 3.0 

CRIMSON BATHING CAP. 

Fine Para 87.0 

Soluble oil red 5.0 

Sulphur 5.0 

Calcined magnesia 3.0 

BLUE BATHING CAP. 

Fine Para 87.0 

Soluble oil blue 5.0 

Sulphur 5.0 

Calcined magnesia 3.0 



PLASTER COMPOUNDS 375 

PLASTERS. 

There are few factories that keep wholly to this line of 
work. It is, perhaps, as simple as any part of the rubber busi- 
ness, a fair grade of rubber being washed, dried, and mixed 
by the usual methods, and calendered upon the fabric that forms 
the base of the plaster. These goods are not vulcanized, of 
course. Though a variety of gums and medicaments are used 
in this compounding, the range is probably smaller than any 
other line of rubber manufacture. 

PLASTER COMPOUNDS. 

POROUS PLASTER. MENTHOL PLASTER. 

Fine Para 50.0 

Burgundy pitch 25.0 Fine Para 30.0 

Gum olibanum ............ 25 .0 Gum olibanum 15 -0 

Medicated as desired. 

MUSTARD PLASTER. Burgundy pitch 15.0 

Fine Para 3.0 Rosin 15.0 

vaseline 75.0 

Benzine 22.0 Orris root 15.0 

The plaster surface is dusted Beeswax . 8.0 

over with mustard flour after 
application to the cloth. Menthol 2.0 



CHAPTER XX. 

GUTTA-PERCHA— ITS SOURCES, PROPERTIES, 
MANIPULATION AND PRINCIPAL USES- 
TYPICAL COMPOUNDS— BALATA. 

Gutta-percha, which was introduced into Europe from 
Singapore in 1843, was for a while confounded with india 
rubber, from which it differs in some very important particu- 
lars. It becomes soft and plastic on immersion in hot water, 
retaining the shape then given it on cooling, whereupon it 
becomes hard, but not brittle, like other gums. India rubber, 
on the other hand, does not soften in hot water, and retains its 
original elasticity and strength unimpaired. The water, as 
such, exercises no softening action on gutta-percha, the effect 
being purely one of temperature, which may equally well be 
produced by hot air, only somewhat more slowly. The degree 
of heat required depends upon the quality of the material, but 
even the hardest kinds become plastic above 150 degrees F. 
Heated in air considerably above the boiling point of water, 
gutta-percha decomposes and finally ignites, burning with a 
luminous smoky flame and emitting a pungent odor resembling 
that from burning rubber. If heated in a vacuum, gaseous 
and liquid products are obtained similar to those resulting 
from the distillation of rubber. The liquid which distils over 
consists chiefly # of hydrocarbons of the terpene series, which 
form an excellent solvent for caoutchouc. The two most 
important are isoprene and caoutchine, which are identical with 
the liquids by the same names obtained from india rubber. 
Since these products can also be obtained from other sources, 
Dr. Eugene Obach and others have observed that they may 
yet form a stepping-stone in the synthetical production of 
india rubber and gutta-percha from the lower terpenes. 

A curious physical characteristic of gutta-percha is that 
when it has been softened in water, although it is so plastic 
that it will reproduce the most delicate impressions, it will 
withstand blows from hammers or may be thrown against 

376 



COMPONENTS OF GUTTA-PERCHA 377 

stone without being marred. The reason is that it contains 
a large amount of air. By subjecting gutta-percha to a vacu- 
um, a large amount of air is withdrawn from the gum, and 
it loses its property of hardening on cooling, its substance 
being like a tough, greasy leather. 

Nowhere on the globe have genuine gutta-percha trees J 
been found outside of an area embracing portions of the Malay ! 
peninsula, Borneo, Sumatra, and adjacent islands. These trees 
belong to the natural order Sapotacece ; the principal genera and; 
and species will be noted further on. 

Pure gutta is insoluble in ether and light petroleum spirit 
at ordinary temperatures, whereas both albane and fluavile 
dissolve readily in them. Gutta possesses all the valuable 
qualities of gutta-percha, but in a much enhanced degree; it 
becomes soft and plastic on heating, and hard and tenacious 
on cooling, without being in the least brittle. But the resins 
themselves at ordinary temperatures are either soft or quite 
friable. It is, therefore, gutta which forms the useful con- 
stituent of gutta-percha, and the resins are only accessory 
components, which, although admissible, and perhaps, even 
desirable in a comparatively small amount, yet have a de- 
cidedly detrimental effect when they preponderate. Hence, 
in order to determine the technical value of a sample of gutta- 
percha, it is necessary first to learn the relative proportion 
or ratio between gutta and resins. There must also be taken 
into account the water enclosed in the mass, and the coarse im- 
purities — wood fibers, bark, sand, etc. — which are described as 
dirt. These components represent the loss or waste to the manu- 
facturer. 

While the relative proportion of gutta and resins forms an 
important criterion for estimating the commercial value of a 
sample, it is not in itself sufficient. Although the analysis of 
two different specimens may give the same result, the physical 
and mechanical properties, and, most important of all, the dur- 
ability, may differ widely, owing to a difference in their mole- 
cular constitution. It will thus be seen that there are guttas 
and guttas. In addition to the qualitative analysis, it is 
necessary to scrutinize the gutta itself, which requires much 
judgment and experience. Analyses have been made of speci- 



378 GUTTA-PERCHA 

mens which contained eight times as much gutta as resin ; 
others contained about an equal amount of both, and in 
still others the amount of resin was three times that of 
gutta. Samples in which the percentage of resin reaches that 
of gutta, or surpass it, are of a decidedly inferior description. 
These differences are due doubtless to the fact that the gutta- 
percha of commerce is derived from trees of various species, 
and also in part to the treatment which the gum receives at 
the hands of the gatherers, who are suspected of mixing the 
product of different trees, to say nothing of adulterations of 
a more debasing character. 

The commercial classification of gutta-percha is less satis- 
factory than that of india rubber, since no standards have be- 
come fixed in the markets. While Para rubber, for instance, 
may be bought and sold by means of established designations, 
"Islands fine," "Upriver fine," and the like, no such practice 
exists with regard to gutta-percha. Since all transactions in 
the latter are based upon samples, trade names and brands 
are little considered. However, "Macassar," and "Bandjer- 
massin," which are the names of districts producing gutta- 
percha, were formerly used to indicate the highest quality, 
while "Sumatra" sorts were supposed to be less valuable, and 
"Borneo" the lowest of all. In a sense these designations 
have become merely commercial, no longer affording any in- 
dication of the origin of the gutta-percha. At the same time, 
"Macassars" and "Bandjermassins" might vary with every 
new arrival, so that one was not certain, in buying one of the 
sorts named, to obtain particularly good gutta-percha; it might 
have been the very opposite. 

Innumerable sorts appear in the Singapore market — which 
is the center of the gutta-percha trade ; but Dr. Obach selected 
twelve of the principal brands as typical of all the rest, and 
divided them into four groups, for convenience in comparison, 
the best being named first. They are as follows, the designa- 
tions being derived either from the countries of their origin or 
from the places of export : 

{1. Pahang — from the Malay peninsula. 

2. Bulongan red — from Macassar, Borneo. 

3. Bandjer red — from Bandjermassin, South Borneo. 

{4. Bagan goolie soondie — from Borneo. 

5. Goolie red soondie — from Serapong, Borneo. 

6. Serapong goolie soondie — from Serapong, Borneo. 



PRINCIPAL GRADES 379 

7. Bulongan white — from Macassar, Borneo. 

III. *! 8. Mixed white — 'from Borneo. 

9. Bandjer white — from Bandjermassin, South Borneo. 

(10. Sarawak mixed — from Borneo. 

11. Padang reboiled — from Sumatra. 

12. Banca reboiled — from Banca. 

Group I comprises the three best kinds, derived from trees 
of the genus Dichopsis (known in continental Europe, as Pala- 
quium). Group II comprises three kinds of the second order, 
derived probably from the genus Payena, Group III embraces 
the so-called "white gutta," of second and third grade, mostly 
of uncertain origin, but probably from Dichopsis polyantha. 
Group IV is made up of mixed materials, two of them being 
what is termed "reboiled," an operation performed by the 
Chinese traders, who buy up odd lots, soften the materials in 
hot water, and make them into a more or less homogeneous 
average mixture. The "Sarawak mixed" lots mostly represent 
a very useful second-class material; the "reboiled" is decid- 
edly inferior. This classification is based upon the results 
of 751 analyses of mixed lots, representing over 5,000,000 
pounds of raw gutta-percha, made by Dr. Obach, with a view 
to arriving at the relative proportions of gutta, resin, dirt, and 
water contained. The cleanest kind is the "Sarapong soondie," 
which contains only 3^4 per cent, of dirt, but it is rather wet, 
having more than 25 per cent, of water. One of the least 
favorable materials is "Bandjer white," which contains 33 1-3 
per cent, of water and 15 per cent, of dirt, making in all nearly 
50 per cent, of waste. When a raw material is very dirty and 
wet, it is noticeable on cutting the blocks open, and this is 
now the rule in the Singapore market. The blocks are then 
sorted out into several grades (two or three, sometimes more), 
according to their appearance, and valued accordingly. 

A grade of gutta-percha which is nearly white in color and 
very brittle is apt to contain a large percentage of resin, which, 
as already explained, renders it of little value. In explanation 
of some of the terms in the preceding classification, it may be 
said that gutta-percha is obtained principally by cutting down 
the trees and ringing the bark at intervals of 12 to 18 inches 
along the trunk. The milky sap in a little while fills the 
grooves cut into the bark, and, in the better varieties, soon 
coagulates, when it is scraped off with a knife. In the case 



380 GUTTA-PERCHA 

of inferior sorts, the milk requires more time to curdle, and has 
to be caught in receptacles placed under the tree. The collected 
milk is then gently boiled, either by itself or with the addi- 
tion of water. The material obtained without the use of water 
is called a goolie, the other a guttaj but the two kinds are 
often mixed together. The goolie is more compact than 
the gutta, and has a dough-like smell. The word soondie is 
derived from the Malay term "gutta-sundek," which is ap- 
plied to the product of trees of the Payena species already re- 
ferred to. 

The processes employed by manufacturers for cleaning 
raw gutta-percha are either mechanical or chemical. Those 
of the first class will first be considered. Generally speaking, 
the raw gutta-percha is either first cut up in a slicing machine 
and then softened in hot water, or the lumps are placed directly 
in hot water and the soft material transferred to the washing 
machine. There it is washed with hot water for a longer or 
shorter time, and then passed through a strainer. Next, as a 
rule, it is washed once more, then put into a kneading or mas- 
ticating machine, to consolidate it and remove the mechani- 
cally enclosed water, and finally it goes to the rolling mill, to 
be made into sheets. 

The slicing machine or chopper now used is pretty much 
the same as that proposed by Charles Hancock, of England, in 
his patent (No. 11,575, O.L.) of 1847, except that it is provided 
with a greater number of fluted and serrated knives, instead of 
only three plain ones, fixed in the slots of a heavy iron disc. 
The blocks of gutta-percha are packed into a trough and then 
forced against the rotating disc, the knives in which cut the 
material into thin slices. 

The washing machine consists of an iron roller of star- 
shaped section, enclosed in a cylindrical shell provided with 
one or two projections, or ribs, against which the gutta-percha 
is forced in going around. The cylindrical shell is enclosed 
in a large iron case, filled with water, which is heated by 
means of direct steam. The dirt, as it is washed off, falls 
through the lower part of the cylindrical shell into the outer 
case, whence it is drawn off periodically. This machine is 
developed from that described in the English patent of R. A. 
Brooman (No. 10,550, O. L.). 



MECHANICAL TREATMENT 381 

•, The gutta-percha leaves the washing machine in a plastic 
state and passes to the straining machine — a strong iron cyl- 
inder with a perforated bottom, on which a number of discs 
of fine wire gauze have been placed. It has a piston which 
is driven home by hydraulic power, at a pressure of 1,500 to 
2,500 pounds per square inch, squeezing the soft gutta through 
the meshes of the gauze. 

The kneading machine or masticator resembles the 
washer, except that the roller is smaller in diameter, and the 
flutings are more numerous and not so deep. The gutta- 
percha is kept hot during mastication and the water escapes 
in the form of steam through openings at the top. 

The mixing machine, introduced by Paul Pfeiderer, is 
similar to that used in the india rubber, linoleum, and other 
similar industries. It is provided with peculiarly shaped 
blades, working against one another. The machine is used 
for mixing the various sorts of gutta-percha, in order to obtain 
a material of requisite properties, and also for blending 
gutta-percha with pigments or other ingredients. The rolls 
can be heated by steam, but heat is developed by the kneading 
process itself, and care must be taken not to overheat the 
material. 

The gutta-percha is next rolled into sheets, usually be- 
tween }i and %. inch, and cut into lengths of 5 or 6 feet, 
and stacked away for use. The rolling machine takes the 
material from the mixer and squeezes it between parallel 
rollers, running it back and forth until it is cool and hard 
enough for cutting up. 

The average percentages of waste, shown by numerous 
analyses of the twelve brands of gutta-percha catalogued on 
a preceding page, are about as follows : 

Pahang 34 Bulongan white 43 

Bulongan red 35 White mixed 35 

Bandjer red 44 Bandjer white 47 

Bagan goolie soondie 32 Sarawak mixed 44 

Goolie red soondie 27 Padang reboiled 44 

Serapong soondie 36 Banca reboiled 29 

The difference in the quality of various brands of gutta- 
percha, measured by the relative proportions of gutta and 
resin, has already been mentioned. Of the sorts mentioned 



382 GUTTA-PERCHA 

above, "Banca reboiled" shows a comparatively small loss in 
cleaning, but it is the least valuable on the list, being low 
in gutta, whereas "Pahang," though losing more in the clean- 
ing process, is by far the most valuable sort in the market, 
because so rich in gutta. Gutta-percha imported in recent 
years loses more in cleaning than formerly; Dr. Obach, in 
1898, estimated the loss as almost twice as great as formerly. 

The chemical washing process was suggested by Charles 
Hancock, in an English patent, in 1846. He steeped raw gutta- 
percha, cut into small pieces, in a solution of caustic alkali 
or chloride of lime, to neutralize the acidity and remove any 
unpleasant odor. His experiments showed that the alkaline 
treatment not only reduced the percentage of dirt — that is, it 
was better cleaned than by the mechanical process — but less- 
ened the capacity of the gutta-percha for retaining mechani- 
cally enclosed water. But the treatment with chemicals 
requires great care and judgment, and thorough subsequent 
washing with water; otherwise the material will be rendered 
perishable. 

Chemicals were also used by Obach for hardening gutta- 
percha. The really valuable constituent of gutta-percha being 
the gutta, the more a sample contains of the latter, the better 
it is, provided the gutta itself is of a good description. For 
certain purposes it is advantageous to improve the hardness 
and other mechanical properties of gutta-percha, and this can 
be done by extracting the resin with a suitable solvent, which 
leaves the gutta itself intact. The raw gutta-percha is first 
chopped and thrown on drying platforms gently heated from 
below by steam pipes. Or the pieces may be thrown into 
a rotating drum heated by currents of warm air. They then 
go to a series of tanks in which petroleum spirit is used as 
a solvent for the resin. The spirit becomes charged with the 
resinous matters, and the resulting solution is distilled off, 
after which the material remaining is masticated as in the 
case of any other gutta-percha. A specimen treated by this 
process will remain quite hard under a temperature which 
will render other specimens soft and plastic. Other liquids 
may also be used, as ether, and a saturated solution of carbon 
disulphide in alcohol. 



GREEN GUTTA-PERCHA 383 

Instead of removing impurities from gutta-percha by- 
washing it either with water or an alkali, this can be done 
by dissolving the material into a suitable liquid, straining or 
filtering the solution, and then evaporating the solvent. Car- 
bon disulphide has been used as the solvent, but with the 
effect of rendering the gutta-percha perishable. 

Recently an article known as green gutta-percha has been 
offered to the trade, being extracted from the leaves of the 
trees. Several systems for extracting gutta-percha from leaves 
have been described. That of Dieudonne Rigole involves the 
use of carbon disulphide; that of Eugene Serullas the use of 
hot toluene as a solvent, after which the gutta-percha is pre- 
cipitated by means of acetone, instead of distilling off the 
solvent; and that of Obach the use of light petroleum spirit 
as a solvent for leaves that have been previously crushed 
between rollers, the gum being reprecipitated from the solu- 
tion on cooling below 60 degrees F. The author of each 
process has devised apparatus for its operation. 

Many trees produce gums which have been experimented 
with in the hope that they would prove good substitutes for 
gutta-percha, but none have proved of value except the "bul- 
let" tree, which yields balata. The gutta contained in balata 
is very strong and tough, being oft excellent quality ; but the 
percentage of resin is large, and the material can be regarded 
as a substitute only for second-class; or, perhaps, even third- 
class, gutta-percha. Balata is somewhat more flexible than 
gutta-percha, containing an equal amount of resin, which 
appears to be due to the softness of the resinous constituents. 
On becoming heated balata behaves much like ordinary gutta- 
percha. If plunged into boiling water it becomes quite solt 
and plastic. If next immersed in cold water, it slowly hardens 
again, but still remains flexible and elastic, showing no signs 
of brittleness. Analyses of specimens of balata from British 
Guiana, obtained from the London docks in 1889-94, showed 
an average loss of 13.8 per cent, of water, and 9.9 per cent, 
of dirt, or a total of 23.7 per cent, of water. The respective 
percentages of gutta and resin were 41.4 and 34.8. 

The specific gravity of cleaned gutta-percha is practically 
the same as that of water, though varying with the relative 



384 GUTTA-PERCHA 

proportion of gutta and resin, becoming lower as the per- 
centage of resin increases. It may be affected, also, by the 
constitution of the resin and also of the gutta. The softening 
temperature of gutta-percha depends entirely upon the ratio 
of gutta and resin. A specimen of which 60 per cent, was 
resin was softened at the temperature of 48 degrees C. to the 
same extent as another specimen, containing only 2^> per 
cent, of resin, for which a temperature of 55 degrees C. was 
required. The time for the material to become hard again, 
after having previously been softened in hot water, depends 
in a like degree upon the proportion of gutta and resin. But 
the principal mechanical property of gutta-percha with which 
the manufacturer has to deal is the tensile strength. A speci- 
men having 45 per cent, of gutta and 55 per cent, of resin 
will break under pressure of 770 pounds to the square inch, 
whereas for another specimen, after most of the resin has 
been extracted with petroleum spirit, nearly twice that break- 
ing strain will be required. As for the elongation of gutta- 
percha — i. e., the extent to which it will stretch before break- 
ing — it is also affected by the percentage of resin, being in the 
last two cases, for instance, 490 and 500 per cent., respec- 
tively, but it also depends on the nature of the gutta. 

The earliest practical use of gutta-percha was for surgi- 
cal appliances — for bandages, splints, and receptacles for vac- 
\ cine virus. It is used for ear trumpets; for the handles of 
surgical instruments, as it affords a firm grip and is prefer- 
able to wood for antiseptic reasons ; in medicine, in the form 
(1) of a very thin tissue, (2) of sticks, and (3) of a 10 per 
cent, solution in chloroform; for chemical purposes, in the 
form of tubes, pumps, syringes, bottles, and the like, and for 
ladles and tubes for handling caustic alkalies and corrosive 
acids and liquids in chemical works ; and for mechanical pur- 
poses, as rings and cups for pumps and hydraulic presses and 
for driving bands (belting). For the latter purpose balata is 
also used largely, interposed between canvas ; such belts can be 
joined by means of a solution of balata or gutta-percha in car- 
bon disulphide. Another application of gutta-percha is that for 
taking impressions of medals, and also of the interior of 
large guns. Gutta-percha is also modeled into ornaments in 



USES IN INSULATION 385 

the shape of the leaves and petals of flowers, this being done 
by working the gum by hand in hot water with one or two 
simple iron tools. Such ornaments are often applied to the 
decoration of jars made of semi-porous ware, the whole being 
painted afterward. 

But the most important application of gutta-percha is in 
the insulation of submarine and subterranean cables. Dr. 
Werner von Siemens first proposed gutta-percha for insulat- 
ing purposes in 1846, and in the next year he designed a 1 
screw press, for the seamless covering of wires with that 
material, which is still in existence, while the principle of 
the press is still adhered to. Gutta-percha has been found 
to be very permeable to the X-rays, and it has been proposed 
to utilize this property to examine gutta-percha-covered wires 
for the detection of defects in the copper conductor, particu- 
larly in "joints," or for finding air-bubbles. The X-rays may 
also be used for the detection of large foreign bodies in the 
raw gutta-percha. 

The electric properties of. gutta-percha depend chiefly on 
the nature of the gutta and to a less extent upon the resin; 
but only very slightly on the relative proportion of these two 
components. They depend also upon the nature and amount 
of the impurities and on the water. The insulation and induc- 
tive capacity are little affected by the extraction of the resin. 
The insulation should be as high as possible, and the induc- 
tive capacity, for most purposes, as low as possible, but 
whereas the latter is mostly associated with other good quali- 
ties of the material, such is not always the case with a high 
insulation. A third electric property is called dielectric 
strength, or resistance to piercing by high voltage. A thick- 
ness of a little over % inch of gutta-percha breaks down with 
40,000 volts, and one of about 1-10 inch with 28,000 volts. 

Gutta-percha hardened by the extraction of its resin is 
used chiefly in the manufacture of golf balls. Gutta-percha 
for this purpose should be tough, elastic, and not brittle at 
low temperatures ; it should be specifically lighter than water, 
in order not to sink if dropped accidentally into a ditch. It is 
requisite that the proper grade of raw material be chosen and 
that the resin be extracted as completely as possible. To test 



386 GUTTA-PERCHA 

the elasticity of golf balls, a machine is used, consisting of (1) 
a perpendicular scale, divided into feet and tenths; (2) a 
clip, at the top, for holding the ball to be tested; and (3) an 
iron plate at the bottom. The object is to measure the re- 
bound of the ball, when released from the clip and falling 
upon the plate. A ball made of gutta-percha, of which 25 
per cent, was resin, rebounded only to the point on the scale 
marked 30 ; a ball containing only 10 per cent, resin rebounded 
to 45 ; and still another, having only a small percentage, re- 
bounded to 60 — the highest point reached. A ball of balata, 
having the resin thoroughly removed, rebounded to 59. 

Some figures will give an idea how greatly the physical 
and mechanical properties of gutta-percha are affected by the 
extraction of the resin. Carefully selected specimens of a 
medium quality were cut fine and intimately mixed, and then 
divided into two portions. One portion was next washed in 
the ordinary way with water; the other treated with petro- 
leum spirit until nearly all the resin had been extracted. The 
two specimens showed the following analyses : 

Gutta Resin Dirt Water Total 

Cleaned in ordinary way 54.7 39.4 2.7 3.2 100 

Same material, hardened 93.0 2.8 2.5 1.7 100 

The different physical and mechanical properties of the 
two specimens are indicated in the next comparison : 

Ordinary Hardened 

Temperature when commencing to soften.. 37.7° C. 57.2° C. 

Temperature when commencing to harden. 58.8° C. 91.1° C. 

Time of hardening 17 min. 45 sec. 

Tensile strength — pounds per square inch . . 1,592 5,662 

Elongation — per cent 360 285 

The electrical properties, on the other hand, are but little 
affected, the insulation being practically the same as before, 
and the decrease of specific inductive capacity is probably due 
to the smaller percentage of water in 1 the hardened material. 

The principal cause of the destruction of gutta-percha is 
the absorption of atmospheric oxygen, which alters the gutta 
and produces a brittle resin of quite a different nature to that 
originally present in the material. This destructive oxidiza- 
tion is greatly assisted by light, and by other causes — for 
instance, by any action tending to make the material porous, 
such as alternate wetness and dryness, the presence of sub- 



CAUSES OF DETERIORATION 387 

stances which exercise a solvent action on gutta-percha as a 
whole or any of its components. Certain alkaline substances 
and decaying organic matters also appear to act injuriously, 
but frequently it is impossible to assign a definite cause for 
decay of gutta-percha. It is, however, not merely manufac- 
tured gutta-percha which undergoes these destructive changes, 
for raw material of the very best kind succumbs in time to 
the combined action of light and air. On the other hand, 
specimens of gutta-percha are in existence which, after proper 
means of protection, have remained in good condition for 
more than fifty years. Complete immersion in water affords 
a good protection, for which reason submarine cores of gutta- 
percha are more safely placed than underground wires. An- 
other way of excluding the air, to some extent, is to varnish 
the gutta-percha articles. When the gutta-percha is oxidized 
it becomes porous and full of cracks. If it be used for insulat- 
ing wires, the insulation fails at such places, since the mois- 
ture penetrates the pores and fissures and establishes an elec- 
tric contact withy the conducting wire. 

Some compounds containing gutta-percha are very useful 
for different purposes, and a specially useful one, consisting 
of a mixture of gutta-percha, colophony, and Stockholm tar, 
is known as "Chatterton's compound." It is used largely in 
connection with the -manufacture of gutta-percha-covered 
wires, as a binding material between the copper conductor 
and the gutta-percha covering, or between the different layers 
of gutta-percha on the core. 

Willoughby Smith patented the following compound for 
insulating wires: one-fifth by weight of Stockholm tar and 
about the same weight of resin are put into a vessel with a 
jacket (or, preferably, a series of pipes) heated by steam ; 
when properly melted the whole is passed through a wire 
gauze strainer "into another vessel similarly heated"; three- 
fifths by weight of gutta-percha, having by preference been 
previously cleansed in the ordinary way and reduced into thin 
pieces or shreds, is then put into the heated vessel and mixed 
with the resin and tar. In this second vessel are stirrers, for 
mixing the whole uniformly. 

Leonard Wray's cable compound was made of 1 part 



388 GUTTA-PERCHA 

gutta-percha, 4 parts india rubber, 2 parts shellac, 2 parts 
flour of glass. This was used for underground wires. 

Gaullie combined gutta-percha with Roman cement by- 
means of animal gall, forming a plastic material, capable of 
being stamped and molded. 

Cooley mixed gutta-percha with resin oil under heat, then 
mixed in carbonate of soda with roasted starch. To this com- 
pound he added asphalt to make it harder, or hyposulphite 
of lead, to make it softer. He also made a great many gutta- 
percha compounds in which salts were present. These he 
steeped in water after mixing until they became soft and 
flexible. 

Charles Macintosh made a compound for telegraph wire 
from gutta-percha, naphthalene, and lampblack. 

Charles Hancock boiled gutta-percha in muriate of lime, 
passed it between heated cylinders, sifting the surface with 
rosin, in the production of a compound for complete insula- 
tion. Another of his compounds was made of gutta-percha, 
shellac and borax. He also made gutta-percha sponge by 
mixing with it carbonate of ammonia or alum and applying 
heat. He also made a hard gutta-percha which was similar 
to vulcanite by mixing it with sulphur, putting it in molds 
and keeping the compound at a high temperature! for several 
days. 

Duncan invented a great many compounds for gutta- 
percha cement, many of which are now in general use. One 
suggestion of his was the mixing of gutta-percha with Canada 
balsam and shellac, the resultant compound being a good 
cement capable of standing considerable heat and in no danger 
of becoming greasy on its surface. 

Robert Hutchinson claimed that he was able to render 
gutta-percha less liable to oxidize, to improve its elasticity, 
increase its tenacity, and diminish its liability to become sticky, 
or tacky, by compounding it with lanichol or wood cholesterin. 
(See Lanoline). 

Forster deodorized gutta-percha by mixing with it essential 
oil, orris root, or gum benzoin. 

Liquid gutta-percha is gutta-percha dissolved in chloro- 
form, to which a little carbonate of lead is added in the shape 
of a fine powder. After agitation, the mixture is set aside 



VULCANIZATION 389 

until the insoluble matter has settled. The clear liquid is 
then decanted. 

Spill, in order to prevent gutta-percha that had been vul- 
canized from being attacked by grease, treated it to a solution 
of melted beeswax, hardening this coating with an infusion 
of nut-galls. 

Godefroy mixed gutta-percha with powdered coconut 
shell, claiming that it would stand a higher degree of heat, 
and was considerably more elastic. Day, in America, mixed 
pipe clay with gutta-percha to prevent its sponging during 
vulcanization. 

The vulcanization of gutta-percha, in spite of a common 
impression to the contrary, is something that can be easily 
accomplished, and is analogous to the vulcanization of india 
rubber. It can be done by mixing with free sulphur or sul- 
phides that contain free sulphur, or by the use of chloride of 
sulphur. As the Parkes mixture attacks gutta-percha very 
easily, the dipping for vulcanization must be very quick, the 
article afterward being allowed to remain in the air for some 
hours. The second dip can be a little longer, as the surface 
is less easily attacked than before. The vulcanized product 
is quite hard and will stand a high degree of heat. Chloride 
of sulphur mixed with bisulphide of carbon can also be incor- 
porated in a solution of gutta-percha and bisulphide of car- 
bon, with the result that the gutta-percha will be thoroughly 
vulcanized. 

The late Robert Dick, of Glasgow, who was a successful 
manufacturer of gutta-percha articles in the mechanical line, 
produced many vulcanizable compounds of gutta-percha of 
great value, some of which follow. He claimed that his com- 
pounded gutta-percha retained the good qualities of the gum; 
that is, that it was homogeneous and plastic at a moderate 
heat, but tough and hard at ordinary temperatures, and that 
it was just as valuable afterward for mixing and molding over 
again. 

Compound No. 1 is described as the hardest and tough- 
est, and may be used, in place of leather and vulcanized india 
rubber for tires, belts, pulley coverings, horse shoes, etc. No. 
2 is softer and more elastic, and suitable for soles and heels 
of shoes, wringer rolls, springs, playing balls, mats, etc. These 



390 GUTTA-PERCHA 

goods are mixed in the usual way, and vulcanized in the masti- 
cator, but not enough to take away the plastic qualities of the 
gutta-percha. For treating this compound, a special masti- 
cator was devised by Mr. Dick, the rolling cylinders being 
hollow, and a Bunsen gas-burner inserted through one end 
of the hollow axle, while the gases pass off at the other, thus 
heating both roller and mixture. The outer cylindrical mas- 
ticator is jacketed and heated with steam: 

COMPOUND NO. I. 

Pure cleaned hard gutta-percha 28 

Pure cleaned tough selected gutta-percha or balata (prefer- 
ably more rather than less) 11 

Pure cleaned "low white" gutta-percha (preferably less 

rather than more) 9 

"Crumb" or ground good old vulcanized india rubber 34 

Hardwood veneer dust 5 

Sulphur . . .i t. ,...>, &/ 2 

Zinc oxide (or zinc dust) 3% 

Flocking, or the cut fiber of cotton textile fabrics 3% 

Total 100 

COMPOUND NO. II. 

Pure cleaned tough gutta-percha 8J4 

Pure cleaned balata or selected gutta-percha 8J4 

Pure cleaned "low white" gutta-percha 24 

"Crumb" or ground good old vulcanized india rubber 33 

Hard ground veneer dust 5 

French chalk, powdered 6 

Sulphur 6 

Zinc oxide (or zinc dust) 3 

Flocking, or the cut fiber of cotton textile fabrics 3 

Alum, ground 3 

Total 100 

Another compound patented by Mr. Dick embraced the 
use of low grade African and Borneo rubbers, which, after 
cleansing, were mixed with gutta-percha, while still moist, in 
hot water. After the mixing the compound is treated under a 
moist heat, where the temperature is 212 degrees to 240 de- 
grees F., the result being a tough, plastic fibrous dough. This 
compound is then, so the inventor claims, equal to any serv- 
ice for which the gutta-percha and balata compounds are 
used. An important property in this compound is the shrink- 
ing quality which gutta-percha possesses, while its power of 
cohesion rendered it especially valuable for insulating wires. 
Shepard mixed gutta-percha with sulphur, exposed it to 
a heat varying from 300 degrees to 350 degrees F., admitting 



COMPOUNDS 391 

hot air, then combined it with sulphur and earthy matters. It 
was then vulcanized by Parkes's cold-curing process. 

Parkes dissolved balata and mixed it with 5 per cent, of 
chloride of sulphur, diluted with mineral naphtha. Gun cot- 
ton was also dissolved to a pasty mass, in naphtha distilled 
with chloride of calcium, and the two solutions were com- 
bined, forming a soft, flexible compound. 

Childs vulcanized gutta-percha by mixing it with sulphur 
and placing it in a vulcanizer containing hydrated lime, and 
then turning on heat sufficient to obtain enough steam from 
the lime to do the curing. 

Duvivier and Chaudet treated gutta-percha with bromide 
of sulphur or chloride of sulphur, making it more elastic and 
less liable to be acted on by heat or cold. When acid vapors 
were formed during the operation, carbonate of sodium was 
mixed with the solution. 

Rostaing made gutta-percha hard and unalterable by 
treating it, after cleansing, with caustic soda, which was thor- 
oughly washed out, after which it was combined with silicate 
of magnesia and treated with tannin, catechu, and other astrin- 
gent matter. 

Keene cured gutta-percha articles by exposing them to 
the fumes of sulphur or immersing 1 them in a bath of melted 
sulphur. 

Charles Hancock treated gutta-percha in a bath of boil- 
ing water in which was carbonate of potash, or muriate of 
lime, leaving it for an hour, and then mixing it with lead, 
glue, and bitumen. His claim was that this treatment hard- 
ened the gutta-percha, rendered it better adapted for bear- 
ing friction, and less likely to be oxidized. He also cured 
gutta-percha by mixing with it sulphur sulphides or orpi- 
ment, and applying heat. He gave as a compound for vul- 
canizing gutta-percha 48 parts gutta-percha, 6 parts golden 
antimony sulphuret, and 1 part sulphur, the compound to be 
boiled under pressure. 

Emory Rider mixed gutta-percha with oxide of lead, 
heated it in open steam heat until the oily matters were ex- 
pelled, then mixed it with hyposulphite of lead and cured it. 

Lucas prepared a printing roll of gutta-percha, first im- 



392 GUTTA-PERCHA 

mersing the gutta-percha in nitric acid, and then placing it for 
an hour in a solution of carbonate of soda, thus producing a 
tougher wearing surface. 

Barlow and Forster mixed gutta-percha with kauri gum 
and milk of sulphur for a cable coating. 

Macintosh immersed gutta-percha in concentrated sul- 
phuric acid for a number of seconds to harden the surface. 
He also mixed gutta-percha with gun cotton, curing with 
sulphuric acid, claiming that the resultant compound was 
not likely to be affected by the heat of tropical climates. 

TYPICAL GUTTA-PERCHA CEMENT COMPOUNDS. 

1. — 'For joining wood: gutta-percha, 11 pounds; shellac, 3 
pounds; Venice turpentine, 5 pounds; pitch, 1 pound. 

2. — For uniting metals, glass, stone, and earthenware: 
gutta-percha, 45 pounds; shellac, 20 pounds; gum mastic, 5 
pounds; oxide of lead, ^ pound; storax, 3 pounds; Venice 
turpentine, 26^2 pounds. 

3. — For cementing leather : gutta-percha, 4 ounces ; bisul- 
phide of carbon, 20 ounces; asphaltum, 1 ounce; common 
resin, 1 ounce. 

4. — Gutta-percha glue: gutta-percha, 1 pound; rosin, 1 
pound; litharge, 1 ounce; powdered glass, quantum sufficit. 

5. — Shoemaker's wax: melt gutta-percha, 20 ounces; add 
pitch, 58 ounces; soap, 5 ounces; rosin, 6 ounces; beeswax, 5 
ounces ; palm oil, 1 ounce ; tallow, 5 ounces. 

6. — For preserving metals and other surfaces: coal tar, 20 
pounds; gutta-percha, 5 pounds; minium, 6 pounds; white 
lead, 7 pounds ; pitch, 10 pounds ; resin, 10 pounds ; spirit tur- 
pentine, 4 pounds; sulphur, 38 pounds. 

7. — General cement : Make a solution of balata of 5 ounces 
in % gallon naphtha, and another of gutta-percha 5 ounces in 
Y\ gallon naphtha. Combine the two solutions and add 13 
ounces resin or pitch and stir and mix thoroughly. 

"Gentsch's gutta-percha" is a widely used substitute for 
gutta-percha, made in general as follows : the ingredients used 
are mineral wax, tar, resin and rubber. The process is thus 
described by a scientist who visited the English factory. A 
mixture of resin, wax, and tar was thrown into a kneading 
machine, steam being applied from below to keep the tem- 



ANALYSIS OF GUTTA-PERCHA 393 

perature at the proper point. Twenty minutes later, the mass 
having been kneaded meanwhile, the steam was turned off 
and the rubber (cut into small pieces) added, being fed in 
slowly to prevent jamming of the knives of the kneading 
machine. The machine was stopped from time to time to test 
the condition of the mass, and at the end of three hours the 
solution of the rubber was found to be complete and the mass 
was removed from the machine and passed between rollers, 
coming out in slabs % inch thick — the finished material. 
THE ANALYSIS OF GUTTA-PERCHA. 

This of course refers to the analysis for the crude gum, 
and, to have the analysis complete, it should cover the amount 
of water present, the amount of foreign matters and impuri- 
ties, the amount of ash, the amount of pure gutta, and the 
amount of resins. 

The water is easily determined by heating a known weight 
from the sample at a temperature ranging from 212 degrees 
to 230 degrees F., the loss in weight being the amount of 
water present. This is a common process in chemical analy- 
sis. In the case of gutta-percha, it must be varied, as the 
sample is liable to oxidize even under examination, causing 
an increase of weight. This is overcome by conducting the 
heating in a slow current of nitrogen, or carbonic acid gas. 

J. A. Montpellier devised an apparatus for this, which 
consisted of a special retort with a large opening which he 
used as a vapor bath and having a tubulure at its side. It is 
closed by a large cork, in which there are two holes, one for 
the tube which is to introduce the gas, and the other for the 
thermometer. The sample to be dried is placed in a crucible 
of porcelain or platinum suspended within the retort. As the 
water evaporates it is borne by the current of gas through 
a tube inserted in the side tubulure, and into U-shaped tubes, 
containing sulphuric pumice, which retain it. Further on 
the U-tubes are connected with a Liebig tube with five bulbs 
containing pure sulphuric acid to prevent the entrance of 
moist air after the apparatus cools, a further use being to 
make it possible to regulate the! speed of the current of gas. 

The retort is immersed in an oil bath heated by a Bunsen 
burner. If carbonic acid be used it is obtained by the action of 



394 GUTTA-PERCHA 

hydrochloric acid on marble chips produced in a Kipp appara- 
tus followed by wash flasks, the first of which contains potas- 
sium bicarbonate in solution, which is intended to stop the 
passage of any hydrochloric acid, and the second containing 
sulphuric acid at 150 degrees to thoroughly dry the gas. To 
be absolutely sure that this gas is dry a desiccator filled with 
sulphuric pumice is placed between the retort and the second 
wash flash. The operation of drying one gram with this 
apparatus takes 6 to 7 hours. The determination of the 
amount of impurities, which comes next, may be effected 
very easily, by using M. J. Jean's exhaust apparatus. A small 
part of the sample, from one-half a gram to a gram, is weighed, 
cut into small fragments, put in a filter, the weight of which 
is known, which ini turn is placed in a platinum cone. This 
cone is then put in the extension of the apparatus ; this exten- 
sion communicates by two tubes with the retort containing 
pure chloroform. A condenser, in which a current of cold 
water constantly circulates in order to condense the chloro- 
form vapor, is placed at the upper part of the extension. 

The retort rests on a sand-bath, very gently heated by a 
Bunsen burner. Under the influence of the slight heat the 
chloroform evaporates, passes through one of the tubes, and 
drops on the filter containing the gutta-percha, which it grad- 
ually dissolves. The solution, passing through the filter, then 
drips into the retort through the second tube. 

All the impurities remaining in the filter, it is sufficient 
to dry and weigh the filter to get the weight of the foreign 
matters. The drying should be done in the apparatus used in 
determining the amount of water. 

The next process is the determination of the amount of 
ash. In gutta-percha this is always very small, as mineral 
matter is almost entirely absent from it, the quantity never 
exceeding one-half of 1 per cent. The amount of ash is deter- 
mined by burning in a capsule of platinum a known weight of 
gutta. 

The fourth step is the determination of the amount of 
pure gutta, and of the resins. Both fluavile and albane are 
soluble in absolute alcohol at the boiling point, and as pure 
gutta is insoluble in it, this is a very ready means of separa- 



ANALYSIS OF GUTTA-PERCHA 395 

tion. The sample to be examined is cut in little bits, put in 
a platinum basket, which is pierced with holes, and hung in 
a retort containing the alcohol. This retort is heated with a 
sand-bath or water bath, the vapor of the alcohol passing 
through a Liebig condenser and returning to the retort. The 
boiling is continued for 5 or 6 hours, with the basket immersed 
in alcohol. It is then raised above the liquid, and the boiling 
continued for 5 or 6 hours more. The latter part of the proc- 
ess removes the last traces of resin. 

The boiling operation being completed, the pure gutta, to- 
gether with the impurities, remains on the filter. There re- 
mains then the drying of the filter in the apparatus used in de- 
termining the amount of water and the weighing of it. The 
loss of weight shown by the gutta-percha corresponds to the 
amount of resins increased by the weight of the water. Sub- 
tracting that weight, already determined, the weight of the 
resins remains. 

Wilton G. Berry, Ph.B., is the author of a monograph on 
the analysis of gutta-percha resins, the basis of which was a 
paper read before the Society of Chemical Industry. In it 
he dealt with the comparative quantitative analysis by treat- 
ment of the previously dried material with acetone, alco- 
holic-potash, and petroleum ether, and extraction of the resins 
in a uniform manner with boiling absolute alcohol, and the 
separation of the extracted resins into their component resins, 
soluble and insoluble in cold absolute alcohol. 
The object was the determination of— 

Saponification value, 

Acid value, 

Ether value, 

Iodine value, 

Acetyle value, 

Methyl value, 

Melting point, solubility, etc. 

— of the individual resins, hoping thus to establish a table of 
values whereby the resins of any given specimen may be iden- 
tified and the identity of the parent gum thus established. 
The gums thus far experimented on are a few specimens 
each of gutta-percha, chicle, Almeidina, tuno, jelutong (Pon- 
tianak), balata, and Payena species. 

It has been found thus far that the resins from several 



396 GUTTA-PERCHA 

specimens of the same gum have practically the same con- 
stants and characteristics, and that the resins from the differ- 
ent species of gums have different constants and character- 
istics — in some widely different, and in the cases of the 
gums above cited sufficiently differing to make identification 
of their parent gum an easy matter. From the gums so 
far examined it is hoped to establish the fact that the com- 
bined evidence of the constants and characteristics of the 
resins, together with the character of the accompanying hy- 
drocarbons, will show that each species of gum varies from 
each other sufficiently to make differentiation of unnamed 
specimens complete, and to establish the fact that every 
specimen of the same species of gum is alike in the charac- 
teristics quoted. 

r£sum£ of analytical work. 

Gutta-percha — Resins, soft, pasty, yellow. 

Chicle — Resins hard, grayish yellow, brittle. 

Tuno — Resins hard, dark yellow, brittle. 

Almeidina — Resins hard, brittle, yellow. 

Jelutong — Resins soft, brittle, yellow. 

Balata — Resins turbid liquid, yellow. 

Payena — Resins similar to chicle resins. 

Saponification Acid 
Value Value 

*Gutta-percha resins 78.5 5 

*Gutta-percha (albane) 83.5 — 

*Gutta-percha (fluavile) 71.45 — 

*Chicle resins 103.1 Trace 

Chicle (resin A) ." 129.0 Trace 

Chicle (resin B) 100.8 Trace 

fTuno resins . . 77.3 5.6 

tjelutong 77.5 Trace 

Almeidina 50.4 11.0 

Balata 69.2 Trace 

fPayena species 103.7 Trace 

*Average of 4 specimens. f Average of 2 specimens. 

While the saponification values of gutta-percha, tuno, and 
jelutong resins respectively are almost identical, their separa- 
tion into component resins corresponding to albane and fluavile 
of gutta-percha gives entirely different results from the latter 
and from each other. The resins of chicle and Payena differ 
as widely and the accompanying hydrocarbons are quite dif- 
ferent. 

Analyses of common gutta-percha, by Edouard Heckel 
and Fr. Schlagdenhauffen : 



ANALYSIS OF RESINS 397 

Gutta 75 to 82 

Albane 19 to 14 

Fluavile 6 to 4 

Total 100 100 

Analysis by Payen: 

Gutta 78 to 82 

Albane 16 to 14 

Fluavile 6 to 4 

Total 100 100 

Gutta-percha is made of a mixture of> hydrocarbons, and 

there is usually present a certain amount of oxygen. According 

to Granville H. Sharpe, F.C.S., its ultimate composition is : 

Carbon 86.36 

Hydrogen 12.15 

Oxygen 1.49 

Total 100. 

[Specific gravity, 0.96285 to 0.99923.] 

The primary analysis of gutta-percha by Sharpe is : 

Hydrocarbon 79.70 

Resin 15.10 

Wood fiber 2.18 

Water 2.50 

Ash 0.52 

Total 100. 

Obach gives the following average results from a large 
number of analyses of each of twelve leading brands or sorts 
of gutta-percha: 

Gutta Resin Dirt Water 

Pahang 78.1 19.2 1.5 1.2 

Bandjer red 67.0 30.2 1.5 1.3 

Bulongan red 68.6 29.0 1.4 1.0 

Bagan 57.5 40.9 1.0 0.6 

Goolie red soondie 55.2 42.9 1.2 0.7 

Serapong 56.2 42.4 0.9 0.2 

Bulongan white 52.2 45.4 1.5 0.9 

Mixed white 49.8 47.4 1.1 1.7 

Bandjer white 51.8 44.1 1.8 2.3 

Sarawak mixed 55.6 40.9 1.8 1.7 

Padang reboiled 50.3 45.8 2.0 1.9 

Banca reboiled 46.8 51.1 1.1 1.0 

Another series of analyses by Obach relate to the con- 
stituents of the resins in gutta-percha, as follows : 

Albane Fluavile 

Carbon 78.76 80.79 

Hydrogen 10.58 11.00 

Oxygen 10.46 8.21 

Total 100. 100. 



398 GUTTA-PERCHA 

BALATA. 

Balata is the gum of the "bully" or "bullet" tree — the 
Mimusops balata — found in British and Dutch Guiana, and in 
Venezuela. It is marketed in two forms, "block" and "sheets." 
The sheet is usually worth about 30 per cent, more than the 
block balata. The sheet is used for belt covering, while the 
block is more used in compounding. Balata is usually red- 
dish gray, though sometimes brown. The dried sheet milk 
or sheet product usually contains 39 per cent, gutta and 37 
per cent, rosin; while the boiled or block contains 51 per 
cent, gutta and 48 per cent, rosin. The sheet shrinks from 
10 to 20 per cent, while the block shrinks from 20 to 30 per cent. 

The balata tree may be tapped when 5 inches in diameter. 
If tapped too deep, the tannin sap injures the product, and the 
wound is slow to heal. The outer bark is removed before 
tapping. The milk runs for about three hours, and a tree 
will generally yield about 3.6 liters of milk, or \ J / 2 to 2 kilos 
of balata. It usually requires about two weeks for the milk 
to dry. 

In character this gum occupies a position between india 
rubber and gutta-percha, combining in a degree the elasticity 
of one with the ductility of the other, and freely softening and 
becoming plastic and easily molded in hot water. Balata is 
dried ordinarily by evaporation. A more rapid coagulation is 
effected by the use of spirits of wine. Alum is sometimes 
used to coagulate, but is not very satisfactory. The gum 
is sometimes mixed; during the gathering with the milk that 
produces gum known as touchpong and barta-balli. It is used 
principally in the manufacture of belting and for insulation 
work. It has been utilized also for golf balls and as a 
substitute for rubber in dress shields. 



INDEX 



Abba rubber 33 

Abies balsamea 158 

Abyssinian gutta 33 

Acacia 155 

Acacia gum 153 

Accelerators 80, 82 

Amino compounds ..83, 197 

Accelerene 83 

Formin 84 

Hexamethylene amine 84 
Hexamethyliene tetra- 

mine 84 

Miscellaneous 84 

Paranitroso dimethyl- 
aniline 83 

Para-phenylenediamine 84 
Tetramethylene dia- 
mine 84 

Ammonium compounds . 82 
Aldehyde ammonia . . 82 
Ammonium borate ... 82 
Quaternary ammo- 
nium bases 83 

Aniline 81 

Carbon bisulphide addi- 
tion products 82 

with aniline 82 

with PP dimethyl x 
methyl trimenthylene 

amine 82 

with dimethylaniline . 82 

with dimethylamine . . 82 

with tetrahydropyrrole 82 

Miscellaneous 86 

Accelemal 87 

Albumen 86 

Annex 87 

Anthraquinone 86 

Antipyrine 86 

Anvico 87 

Caustic alkali and gly- 
cerol 87 

Dry aniline 87 

Duplex 87 

Excellerex 88 

Formanilide 86 

Magnesia 86 

Naphthylamine 86 

Paradin 88 

Quicklime 87 

Tensilite 88 



Accelerators — Continued. 

Miscellaneous — Continued 

Thioformanilide 86 

Urea 86 

Velocite 88 

Velosan 88 

Vitaminex 88 

Vulcacit 88 

M. C. C 88 

Piperidine derivatives. . . 84 

Aminopentane 84 

Methyl piperidine .... 85 

Piperidine 85 

Quinoline and derivatives 85 
Hydroxy quinoline . . 86 

Oxiquinoline 85 

Oxiquinoline sulphide. 85 
Oxyquinoline sulphonic 

acid 85 

Quinoline 85 

Quinoline sulphate ... 85 

Quihosol 85 

Accra rubber 20 

Acetic acid 48, 194 

Acetone 230 

Achras sapota 35 

Acid, Acetic 48, 194 

Boracic 199 

Carbolic 199 

Chromic 200 

Citric 200 

Formic 48, 201 

Hydrochloric 201 

Mimo-tannic 202 

Muriatic 202 

Nitric 202 

Oleic 203 

Oxalic 203 

Salicylic 206 

Sulphuric 210 

Tannic 211 

Tartaric 211 

Tungstic 212 

Acid cure 54 

Acids, alkalies and derivatives . . 194 

Acroides gum 153 

Action of metals on rubber 262 

Foden on 262 

Morgan on 263 

Schidrowitz on 263 



399 



400 



INDEX 



Adamanta 119 

resin 154 

Adam's process for uniting rub- 
ber to metals 260 

Addah Niggers rubber \ 20 

Adhesor 119 

African rubbers 17 

rubber sources 9, 17 

Agalmatolite 89 

Air brake and signal hose tests . . 343 

Alcohol 48, 230 

Denatured 231 

Alexander's reclaiming process. 295 

Alexite 141 

Algin gum 119 

Allard's fireproof felt 255 

Almeidina rubber 33 

Alstonia plumosa 41 

Alum 48, 194 

Alumina 89 

Aluminite 89 

Aluminum flake 89 

lanolate 213 

oxide 89 

sulphate 195 

Alundum 89 

Alying's rubber cure 58 

Amazonian resin rubbers 34 

Amber 154 

Burmite 158 

resin substitute 119 

Ambriz rubber 23 

Ambroin 141 

American process zinc oxide 190 

American showerproofing com- 
pounds 252 

American Society For Testing 
Materials ; meth- 
ods of analysis 321 

Amianthus 91 

Ammonia 196 

Ammonium carbonate 196 

chloride 197 

muriate 197 

tungstate 197 

Amole juice 48 

Amorphous sulphur 63 

Amphiboline 89, 255 

Analyses of oil substitutes (table) 118 
Anderson's reclaiming process . . 295 

Angola rubbers 23 

Angostura rubber 13 

Anhydrite 90 

Aniline 197 

colors for rubber 177 

Anime 155 

Ant wax 40 



Anthracene 239 

Antimony 90 

crimson sulphide 184 

golden sulphide 191 

iodide 198 

oxide 90 

red sulphuret 66 

Antipolo gum 34 

Apocynacece 7 

Arabic Gum 155 

Argillaceous red shale 90 

Arkosite 155 

Armalac 141 

Arsenate, Potassium 204 

Arsenic 90 

yellow 191 

Artemisia absinthium 227 

Artocarpacea 7 

Artocarpws incisa 34 

integrifolia 35 

Aruwimi rubber 22 

Asbestic 91 

Asbestine 91 

Asbestonit 120 

Asbestos 91 

Analysis of 92 

Ascle'piadacecB 7 

Asphalt 155 

Artificial 156 

French 162 

Lithro-carbon 165 

Manjak 166 

Mineral india rubber . . . 166 

Retin 170 

Trinidad 174 

Assam rubber 25 

white 38 

Assinee rubber 20 

Astragalus gummifera 174 

Astrictum 120 

Attalea excelsa 45 

Atmido 92 

Atmoid 92 

Attoaboa rubber 20 

Aureolin 192 

Aylsworth's Condensite 144 

Axim rubber 20 

A. R. D. Gum 119 

Baka gum 34 

Bakelite 142 

Balata 398 

analyses of 383 

Balenite 142 

Ball, African 18 



INDEX 



401 



Balsam 156 

Canada 158 

of storax 156 

of sulphur 156 

Tolu ... 174 

Balsams in rubber compounding 153 

Banana rubber 34 

Bangui rubber 22, 378 

Bannigan rubber cure 57 

Barabarja rubber 24 

Barberis vulgaris 192 

Barberry yellow 192 

Barium carbonate 92, 95 

chloride 198 

sulphide 64 

white 186 

Barlow and Forster's gutta-per- 
cha compound 392 

Barta-Balli gum 34 

Barytes 92 

Baschnagel's reclaiming process. 293 

Basle's reclaiming process 296 

Bassam rubber 19 

Bassia Parkii 37 

Basofor 93 

Batanga ball rubber 21 

Bathurst rubber 19 

Bayin rubber 20 

Beadle and Stevens, analyses of 

Hevea latex 44 

bleaching of crude rubber 53 
mechanical impurities in 

crude rubber 309 

Beckton White 187 

Beeswax 156 

Beira rubber 35 

Belgian Congo rubber 22 

Belledin's process for leather 

impregnation 120 

Benguela rubber 23 

Benin ball rubber 21 

Benton, preservation of rubber 

goods 258 

Benzene 232, 240 

Benzine 239, 240 

Benzoin 157 

Benzol 232 

Benzole 232 

Bernstein, vulcanization by ultra 

violet rays 61, 62 

Berry, analysis of gutta-percha 

resins 395 

Besk 26 

Beta separator 50 

Betite 142 

Beverly Rubber Works 293 

Beylikgy's reclaiming process... 295 

Biborate, Sodium 207 

Bichromate, Potassium 204 



Birch-bark tar 157 

Biscuits, African 19 

Bisulphate, Potassium 204 

Bisulphide, Carbon 234 

substitute, Carbon 234 

Bisulphite, Sodium 208 

Bitumen 157 

Auvergne 157 

Black, Antimony 93 

Bone 179 

Carbon 179 

Gas 179 

Graphite 179 

Hydrocarbon 179 

Hypo 63, 178 

Jet 179 

Lamp 179 

lead 93 

Paris 180 

pigments for rubber.... 178 

pitch 158 

Satin gloss 180 

Blanc fixe 93 

Blandite , 120 

Blandy's patent substitute 120 

Bleaching powder 198 

Blown oils 213 

Blue, Chinese 181 

Chrome 181 

Cobalt 181 

Indigo 181 

lead 93 

Molybdenum 181 

pigments for rubber .... 180 

Prussian 181 

Saxon 181 

Smalts 182 

Thenard's 182 

Ultramarine 182 

Yale 183 

Bolivian rubber 12 

Bone ash 94 

black 94 

naphtha 237 

Book gutta 26 

Boots and shoes, Compounds for 360 

Dry heat cure of 358 

Manufacture of 357 

Pressure cure of 359 

Varnish for 361 

Boracic acid 199 

Borate, Zinc 187 

Borax 199, 207 

Borcherdt's compound 120 

Borneo rubber 25 

No. 3 38 

Borracha 14 

Bosanga rubber 48 

Botany Bay gum 153 



402 



INDEX 



Bougival white 187 

Bourn's reclaiming process 294 

Brassica campestris 225 

Brierly's patent artificial elater- 

ite 120 

Brimmer's reclaiming process .. 296 

British gum 158 

Brittleness in rubber goods .... 257 

Brixey's Kerite formula 128 

Bromine 64 

Brooksite 143 

Brosimum galactodendron 37 

Brown pigments for rubber 184 

Brown's hard rubber substitute. . 143 

Bucaramanguina 94 

Buki rubber 23 

"Bullet" tree gum 398 

"Bully" tree gum 398 

Bumba rubber 23 

Burgundy pitch 158 

Burmite amber 158 

Burnt hypo 63 

umber 94 

Bussira rubber 22 

Butanes, Rubbers from 272 

Button lac 158 

Buttons, African 19 

Butyrospermum Parkii 38 



Cadmium yellow 192 

Cadoret's resinolines 134 

Calamine 94, 187 

Calcium carbonate 94 

chloride 199 

oxalate 199 

oxide 199 

phosphate 94 

sulphate 95 

sulphide 199 

white 95 

Calculation of analyses 320, 321 

Calendering rubber 353 

Calomel 95 

Calonyction speciosum 48 

Calotropis gigantea 40 

Cameroons rubber 21 

Cameta rubber 11 

Campbell and Cushman's punc- 
ture fluid 266 

Campbell's Endurite 124 

Camphene 233 

Camphor 158, 233 

Oil of 214 

Canada balsam 158 

Candelitta wax 159 

Candle tar 159 



Canoe gums 35 

Caoutchene 121 

Caoutchite 121 

Caoutchouc aluta 143 

oil 214 

Caoutchoucine 234, 376 

Cape Coast rubber 20 

Carbolic acid 199 

Carbon bisulphide 234 

bisulphide substitute . . . 235 

black 179 

tetrachloride 235, 244 

Carbonaceous clay 95 

Carbonate, Barium 95 

Potassium 204 

Sodium 208 

Carbo-nite 143 

Carburet of iron * 95 

Cam gum 159 

Carnauba wax 159 

Carrol gum 121 

Carr's patent cereal gum 121 

Carsel yellow 102 

Cartagena rubber 15 

Casein 159 

Caspari crude rubber valuation 

methods 308 

tetrabromide method for 
determining rubber. 310 

Castilloa elastica 9 

tunu 43 

Ulei 9 

Castilloa plantation rubber 31 

Castor oil 214 

Catechu 200 

Cativo gum 35 

Cattimandu gum 35 

Cauchin rubber 39 

Caucho rubber 13, 14 

Caulbry's rubber cure 60 

Caustic potash 205 

soda 209 

Caviana rubber 11 

Ceara rubber 16 

plantation rubber • 31 

Cellit 143 

Cellulith 143 

Celluloid 143 

Cellulose 143 

Cement, Gutta-percha 392 

Portland 108 

Rubber ....^. 372 

Central American rubber 14, 31 

plantation rubber 31 

Cellazote 267 

Ceramyl 159 

Cerasin 160 

Ceratonia siliqua 174 



INDEX 



403 



Cereal rubber 121 

Ce-re-gum 144 

Ceylon rubber 29 

Chalk 95, 113 

Charcoal, Animal 96 

Vegetable 96 

Charlton white 187 

Chatterton's compound 144, 387 

Chautard's reclaiming process . . 296 

Cherry gum 160 

Chicle gum 35 

substitute 121 

Child's gutta-percha compound 391 

"China clay 96 

Chinese blue 181 

white ...187, 190 

Chloride of lime 198, 200 

Propylene 244 

Sodium 208 

Sulphur 65 

Zinc 212 

Chlorine 64 

Chloroform 236 

Cholesterin 214 

Christia gum 121 

Chrome blue 181 

green 183 

yellow 192 

Chromic acid 200 

Chute's rubber resin solvent .... 236 

Citric acid 200 

Clapp's reclaiming process 293 

Classification of gutta-percha.. 378 

Clift's reclaiming process 296 

Clothing, proofing and carriage 

cloth, Compounds for 364 

Manufacture of 364 

Coagulation of rubber latex.. 44, 45 

by drying 46 

by smoking 45 

Chemical 46 

Electric 52 

Frank-M arckwald's 

process for 51 

Leva process for 46 

Machines for 50 

Mechanical 47 

Purpose of 45 

Coal, Powdered 109 

naphtha 239 

tar 160 

Coalite pitch 160 

Coarse Para Rubber 11 

Cobalt blue 181 

yellow 192 

Coccus lacca 171 

Coconut water 48 

Cod-liver oil 214 



Coefficient of vulcanization and 

state of cure 347 

Cohuru's waterproof compound.. 255 

Colcothar 184 

Cold cure 54 

Colophane 160 

Colophony 160 

Colors, Aniline 177 

Colombian rubber 15 

Colza oil 215, 225 

Combined sulphur, Dr. Stevens 
and Dr. De Vries 

on 347 

Compo 96 

Composites 7 

Composition of rubber 8 

Compound, Barlow and Forster's 392 

Chatterton's 144, 387 

Child's 391 

Cooley's 388 

Dick's 389,390 

Duncan's 388 

Duvivier and Chaudet's.. 391 

Forster's 388 

Gaullie's 388 

Godefroy's 389 

Hancock's, Charles.. 388, 391 

Hutchinson's 388 

Keene's 391 

Lucas's 391 

Macintosh's 388, 392 

Parkes's 391 

Rider's, Emory 391 

Rostaing's 391 

Shepard's 390 

Smith's, Willoughby 152, 387 

Sorel's 151 

Spill's 389 

Wray's, Leonard ...152, 387 
Compounds, boot and shoe, Rub- 
ber 360 

Cement, Rubber 372 

clothing and carriage 

cloth, Rubber 364 

Dental and stamp gum . . 373 
Druggists', stationers' 
and surgical rub- 
ber goods 363 

Gas-tight rubber . . .261, 262 

Gutta-percha 387 

Hard rubber 371 

insulation, Rubber . . 369 

Kiel's hard rubber 148 

Mechanical rubber goods 355 
Molded rubber goods . . . 370 

Notion-trade rubber 374 

plaster, Adhesive 375 

tire, Rubber 367 



404 



INDEX 



Compounding, Reasons for rubber 89 

Waxes in rubber 153 

Conakry rubber 19 

Con-current rubber 122 

Condensite 144 

Congo Free State rubbers 22 

plantation rubber 31 

Consolidated oil 215 

Cooley's artificial leather ...102, 156 
gutta-percha compound 388 

Coorongite 36, 160 

Copal 160 

Copper sulphate 200 

Coralite 145 

Corimite 145 

Cork 97 

leather 122 

Corkaline 122 

Corn oil 215 

substitute 122 

Cornite 145 

Cornwall clay 97 

Corundum 97 

"Coruscus" finish 98 

Corypha cerifera 159 

Costus afer 48 

Cottonseed oil 215 

Couma utilis 37 

Coutinho's machine 50 

Cow tree rubber 37 

Coyuntla juice 48 

Cravenette process 251 

Cream of tartar 201, 204 

Creosote oil 215 

Croton draco 171 

Crude rubber, Bleaching of 53 

Cause of color in ...... 52 

Mechanical and chemical 

relationships of . . 345 
Physical tests and analy- 
ses of 302 

Shrinkage of 263 

African grades of. .263, 264 

Calculation of 265 

East Indian grades of 264 

Para grades of 263 

Valuation of 303 

Classification in 306 

Correlation of tests in 305 
Estimation of moisture 

in 310 

Estimation of rubber in 310 
Fol's conclusions on.. 304 
Form for reporting . . . 310 
Gorter's viscosity in- 
dex in 306 

Mechanical impurities 

in 309 

Moisture in 310 



Crude rubber — Continued 

Valuation of — Continued 
Nitrogenous insoluble 

matter in 309 

Practical considera- 
tions on 309 

Schmitz method for. 309 
Outline scheme for . . . 304 
Physical and mechani- 
cal 311 

Adhesive tests in ... 311 
Mechanical tests in.. 311 
Viscosity tests in... 311 
Vulcanization tests in 311 
Secondary products 

(rubber resins) in 308 
Schidrowitz method of 307 
Scientific method for.. 304 
Tetra-bromide method 

for rubber in ... 310 

Washing loss in 311 

Cumai rubber 37 

Cumaka-balli 35 

Cutch 200, 201 

Cyanide, Potassium 205 

Cyco 266 



Daft's process for uniting rub- 
ber to metal 261 

Dammar 161 

Dankwerth's Russian substitute 122 

Danin's machine 50 

Day's Kerite 127 

use of pipe clay 108 

DaCosta's apparatus 51 

Denatured alcohol 231 

De Pont's substitute 145 

Dental and stamp gum, Com- 
pounds for 373 

Manufacture of 373 

Deodorization process 116, 256 

Bourne's 256 

Cattell's 256 

De la Granja's 256 

Freeley's 256 

Hancock's, Charles 256 

Lavater and Tranter's.. 256 

Traun Rubber Co.'s 257 

Dermatine 122 

Derry's waterproof harness oil. 226 

Dextrine 161 

Dextrose 161 

Diatite 145 

Diatomaceous earth 98 

Dichlor-ethylene 236 

Dichopsis elliptica 41 

polyantha 379 



INDEX 



405 



Dick's gutta-percha compounds 

389, 390 

Dieffenbach's rubber cure 56 

Dimethyl butanes, Rubbers from 272 

Dippel's oil 236 

Divisions of rubber manufacture 354 

Doebrich's compound 123 

Donaldson's electrolytic method 

for lead and zinc. 332 
Doremus fireproofing process . . . 255 

Dow's inner-tube filler 266 

Druggists', stationers' and surgi- 
cal sundries, Com- 
pounds for 361 

Manufacture of 363 

Dry heat cure 54 

mixing 359 

Rubber 352 

Fillers in 89 

Unusual 114 

Drying oil 227 

Dull finish 113, 221 

Dumas' canvas sail waterproof- 
ing 255 

Duncan's gutta-percha compound 388 
Durant patent for bleaching gut- 
ta-percha 236 

Durate 123 

Durvez's reclaiming process 296 

Dutch Congo ball rubber 22 

liquid 237 

pink 192 

Duvivier and Chaudet's gutta- 
percha compound. 391 
Duvivier's gutta-percha com- 
pound 107 

Dyeing rubber 247 

Frankenburg's a n i line 

lakes for 249 

Hoffer's method for 247 

Parkes' formulas for 247 

Dyera costulata 26 

Earth wax 161 

East Africa rubbers 23 

East Indian rubber 25 

Sources of 9 

Eaton, B. J. and Grantham J., on 

optimum cure . .71, 73 

Eaton's, A. K., rubber cure 56 

Ebner's patent A. R. D. Gum... 119 

Ebonitine 145 

Eckstein's Hyaline 147 

Ekert's high pressure composition 123 

Elasteine 123 

Elastes 266 

Elastic glue 123, 161 

Elasticite 123 



Elastite 123 

Elaterite 130, 161 

Artificial 119 

Elateron hydrocarbon 131 

Electric coagulation process 52 

curing process 63 

finish 98 

properties of gutta-per- 
cha 385 

Electroplating on -rubber, Good- 
year's method of. . 248 

Electrose 145 

Elemi 162 

Elmer's rubber cure 59 

Elworthy's process for preserving 

rubber goods 258 

Emarex mineral rubber 131 

Embossing rubber 248 

Bourbridge method for.. 248 

Emery 98 

Endurite 124 

English shower nroofiing com- 
pound 253 

Entrefina Para rubber 10 

Enzymes in crude rubber 52 

Equateur rubber 22 

Esbenite 145 

Esmeralda rubber 15 

Ether 237 

Ethyline chloride 237 

Eucaliptia 215 

Eucalyptus globulus 216 

Eucalyptus oil 216 

Eucommia ulmoides 42 

Euphorbia drageana 40 

fulva 41 

lactiflua 34 

rhipsaloides 34 

rubber 34, 124 

tirucalli 34 

trigona 35 

Euphorbiacea 7 

Euphorbium, Gum 162 

Eureka vulcanizing compound . . 63 

Everlastic 266 

Eves's reclaiming process 296 

Fagioli puncture fluid 266 

Falke and Richard's rubber cure 56 

Faraday's analysis of latex 266 

Fard's Spanish white 188 

Farina 98 

Faure's reclaiming process 294 

Fayolles' substitute 124 

Feldspar 99 

Fenton's artificial rubber 124 

Fiber, Vulcanized 152 

Fibrine-Christia gum 124 



406 



INDEX 



Fibrone 146 

Fichtelit 162 

Ficus elastica 9 

Indica 39 

obligua 34 

Vogelii 9 

Fig juice proofing 124 

Fillers in dry mixing 89 

Fine Para rubber 10 

Fire clay 99 

Allard's 255 

Doremus' 255 

Dumas' 255 

proofing 255 

Firmus 124 

Fish glue 162 

oil 216 

Flake, African '. 18 

Flint 99 

Liquor of 202 

Florence zinc 190 

Flour, Glass 99 

Phosphate 99 

Fluoride, Silicon 206 

Fluvia 26 

Fol on valuation of crude rubber 304 

Formic acid 48, 201 

Forster's gutta-percha compound 388 
showerproofing com- 
pound 254 

Fossil farina 99 

flour 99 

meal 99 

Forsteronia gracilis 39 

Fouquieria splendens 40 

Frankenburg's aniline lakes 249 

non-inflammable rubber 

solutions 230 

puncture fluid 266 

Frankincense 162 

Franklin substitute 125 

Frank-Marckwald's coagulation 

process 51 

French asphalt 162 

chalk 100 

Congo rubber 21 

gutta-percha 125 

process zinc oxide 190 

reclaiming process 296 

talc Ill 

West Africa rubbers ... 19 

wool grease 216 

Frost rubber 125 

Fuller's earth 100 

Fulton white 188 

Fumero of van den Kerckhove.. 51 

Funtumia elastica 9 

kickxia 46 

Fusel oil 231 



Gaboon rubber 21 

Galalith 146 

Galipot 171 

Gambia niggers 19 

Gambie rubber 19 

Gamboge 162, 193 

Gambria 26 

Garicinia morella 193 

Garnet lac 163 

Garnier's rubber cure 60 

Garrity and Avery's process for 
uniting rubber to 

metals 260 

Gas proofing 261 

Bousfield's 261 

Churrel's balloon 261 

compounds for ..... .261, 262 

Pellen's 261 

Gascardia Madagascariensis 40 

Perrieri 40 

Gasoline 237 

Gaullie's gutta-percha compound 388 

Gelatine, Glugloss 163 

Genasco hydrocarbon 131 

Gerard's rubber cure 68 

German black substitute 120 

showerproofing com- 
pounds 252, 254 

Gerner's Heveenoid 126 

Gilbert-Besaw's reclaiming proc- 
ess 296 

Gilsonite 131, 163 

Glass, Flour of 99 

Soluble 210 

Glucose 163 

Glue 163 

Elastic 161 

Fish 162 

Waterproof 139 

Glugloss gelatine 163 

Gluten 164 

Glycerine 216 

Goa gum 37 

Godefroy's gutta-percha com- 
pound 389 

Gold Coast rubber 20 

Gold, Oxide of 100 

Golden antimony sulphide 66, 191 

Golding's Rubberic, Formula for 135 
Goldstein's unvulcanized washers 138 

Golf balls, Gutta-percha 385 

Hard core 146 

Goodyear's, Charles, hot vulcan- 
ization 55 

lead acetate patent 101 

triple compound 114, 248 

Nelson, india rub ber 

leather 126 



INDEX 



407 



Gossypium herbaceum 215 

Gottsch, methods for analyzing 

vulcanized rubber. 329 

Grahamite 131 

Grand Bassam rubber 20 

Grape rubber 125 

Graphite 100 

black 179 

Graves' Rubberite, Formula for. 135 

Grease, French wool 216 

Green, Chrome 183 

gutta-percha 383 

Hungarian 183 

pigments for rubber 183 

Saxon 183 

Terra-verte 183 

Ultramarine 184 

Gregory and Thorn's reclaim- 
ing process 297 

Grena Mexican rubber 31 

Greytown scrap rubber 14 

Griffith's white _ 188 

Griscom's substitute 125 

Grist's Oxolin 132 

Gront and Moore's repair cement 125 

Guatemala rubber 15 

Guayaquil strip rubber 15 

Guayule rubber 16 

Gubbin's reclaiming process 297 

Gum acacia 153 

Acroides 153 

Ammoniacum 154 

anime 155 

arabic 155 

Botany Bay 153 

British 158 

camphor 158 

carbo 125 

Carn 159 

Carrol 121 

Cherry 160 

copal 160 

dammar 161 

elemi 162 

euphorbia 34 

fibrine 125 

goa 37 

juniper 165 

Kauri 165 

lini 165 

Manila 166 

myrrh 167 

olibanum 167 

sandarac 171 

Seiba 42 

Senegal 171 

Spruce 173 

thus 174 

tragacanth 174 



Gum — Continued 

tragasol 174 

Xanthorrhcea 175 

Gun cotton 146 

Gutta. Bassia 37 

Book 26 

Cotie 27 

Grek 37 

Grip 38 

Horfoot 37 

Jintawan 39 

Karite 38 

Penang 27 

Percha 26, 376 

analyses of . .393, 396, 397 

Artificial, French 120 

Bandjermassin 26, 378 

cements 392 

Classification of ...... 378 

Cleaning of 380 

Qiemical 382 

Mechanical 380 

compounds 387, 392 

destruction. Causes of 386 
Dielectric strength of. 385 

Effect of heat on 376 

Electric properties of. 385 
extracted from leaves. 383 
French substitute for. 125 

golf balls 385 

Green 383 

Hard 385, 386 

Indian 41 

Liquid 388 

Macassar red 26, 378 

Properties of 384 

Reboiled 379 

resins 395 

Specific gravity of .... 383 

Uses of 384 

Vulcanization of 389 

waste 293 

Waste of 381 

Pure 377 

Shea 37 

Siak 26 

Souni 27 

Susu 38 

Yellow 43 

Guttaline 125 

Gypsum 100 

Half Jack rubber 20 

Hall's reclaiming process 293 

process for uniting rub- 
ber to metal 260 

Hancock's gutta-percha com- 
pounds 388, 391 



408 



INDEX 



Hancock's — Continued 

vapor cure 60 

Hancornia Speciosa _. . . . 16 

Hard rubber compounds 371 

Manufacture of 141, 371 

substitutes 141 

Harmer's substitute 126 

Harries' formula for rubber 271 

rubber researches 271 

Harris's rubber cure 56 

Hatchetine 166 

Havermann's rubber cure 38 

Hayward's reclaiming process.. . 294 

Heat cure 54 

Hebblewaite and Holt's process. 251 
Heckel and Schlagdenhauffen's 
analyses of gutta- 
percha 396 

Heinrichsen and Marcusson on 

rubber resins 308 

Heinzerling's reclaiming process, 

294.297 
Helbronner and Bernstein's ultra 

violet rays cure. 61, 62 

Helenite 164 

Heifer's process for coagulation. 49 

Helm's rubber cure 58, 65 

Hematite 184 

Henriques' analysis of vulcan- 
ized rubber 312 

analyses of oil substi- 
tutes (table) 118 

Henri's ultra violet rays cure . . 61 

Heptane 237 

Hermizing process 57 

Hevea Brasiliensis 9 

latex, Analysis of 44 

Plantation 71 

Heve rubber 39 

Heveenite 126 

Heveenoid 126 

Heyl-Dia's reclaiming process . . 297 
Hinrichsen's review of synthetic 

rubber 270 

Honduras strip rubber 15 

Honeycomb sulphur 67 

Hopkinson's Vulcanine 139 

Hungarian green 183 

Hunter's Ossein patent 106 

gutta-percha compound. 388 

Lanichol 218 

Huth's Insulite 126 

Hyaline 146 

Hyatt and Penn's reclaiming 

process 297 

Hydrocarbon black 179 

rubber 126 

Hydrochloric acid 201 

Hydrogen peroxide 201 



Hydrolaine 126 

Hydrolene 217 

Hyposulphite, Lead 67 

Sodium 209 

Idrialin 164 

Idrialit 164 

Ikelemba rubber 23 

India rubber leather 126 

Solubility of 228 

Indian gutta-percha 41 

hemp rubber 39 

red 185 

Indigo blue 181 

Indigofera 181 

Infusorial earth 100 

Inrig 267 

Insolacit 147 

Insulate 147 

Insulated wire, Compounds for. 369 

Manufacture of 368 

Insulation, Bureau of Standards' 
methods of analy- 
sis of 319 

Compounds for 369 

Mavall's tape . . » 107 

Mulholland's 107 

Joint Rubber Insulation 
Committee's out- 
line of analysis of 

(table) 322 

Specification for 30 per 
cent. Hevea 333 

Submarine cable 387 

Insullac 147 

Insulite 126 

Iodide, Zinc 212 

Iodine 67 

Ipomcea bona-nox 48 

Ireson's packing compound 126 

Iron, Carburet of 95 

oxide red 185 

peroxide 185 

pyrites 101 

Isanga rubber 23 

Isinglass 164 

Islands fine Para rubber 11 

Isolatine 147 

Isoprene 237, 271 

Rubbers from 272 

Itaituba rubber 11 

Jackson's printers' rollers com- 
pound 126 

Japan wax 217 

Java rubber 25, 29 



INDEX 



409 



Jelutong 25, 39 

resin 164 

Jequie rubber 16 

Jet black 179 

Jeve rubber 39 

Jintawan gutta ^ 39 

Johnstone's non-drying compound 127 
Joint Rubber Insulation Commit- 
tee, Calculation of 

analyses of 321 

Methods of analysis of, 

321, 322 

outlines of analysis 322 

Requirements of specifi- 
cations of 333, 334 

Specifications, by whom 

adopted 337 

Jones' substitute 127 

Joselyn's rubber cure 57 

Jungbluth's compound 127 

Juniper gum 165 

Just's acid-proof composition... 127 

Kamptulicon 127 

Kaolin 101 

Kapak 131 

Karavodine's reclaiming process 297 

Karite gutta 38 

Kasenoid 147 

Kassai rubber 23 

Katanga rubber 23 

Kau Drega gum 41 

Kauri gum 165 

Keene's gutta-percha compound. 391 

Kelgum 127 

Kellog's Kelgum 127 

Kelley's process for bronze effect 
o n rubber-coated 

fabrics 249 

Kempeff's hard rubber substitute 147 

Keratite 147 

Keratol 147 

Kerite 127 

Formula for 128 

Kermes 101 

Kerosene 217 

Kessler's reclaiming process 297 

Kyanizing process 254 

Kiel's compounds 148 

Kieselguhr 101 

King's yellow 192 

Kirrage compound 128 

Kittel's reclaiming process ..... 297 
Klein, Link and Gottsch's aniline 
method for analy- 
sis of vulcanized 

rubber 323 

Koalatex 49 



Koener's reclaiming process 297 

Kommoid 128 

Koneman's reclaiming process 297 

Kornite 148 

Kremnitz white 188 

Kwilu rubber 23 

La Belle's mineral rubber 131 

Laboratory, Equipment of works 303 

Lac 171 

Button 158 

Garnet 163 

Mexican 171 

Mineral 153 

Lactitis 148 

Lagos rubber 21 

Lahou rubber 19 

Lake Leopold rubber 22 

Lallemantia iberica 218 

oil 218 

Lamina fiber 149 

Lampblack 179 

Lamplough's Volenite 138 

Lamu ball rubber 24 

Landolphia 7 

Carpodinus 9 

Clitandras 9 

Lang's Novelty rubber 131 

Lanichol 218 

Lanolate, Aluminum 213 

Lanolin 218 

Lard oil 219 

Larix Europea 245 

Lascelles-Scott on naphtha 240 

methane rubber solvents 239 

on mineral wool 105 

Latex. Rubber 8 

Adulteration of rubber.. 34 

Amapa 34 

Molango 34 

Sucuba 34 

Surva 34 

Tamanguiro 34 

Analysis of Hevea . . 44, 266 

Lavender oil 219 

Lavandula vera 219 

Lead acetate 101,202 

Blue 93 

carbonate 101 

nitrate 202 

oxide 102 

oxychloride 102 

peroxide 102 

Red 110 

Sublimed 112 

Sugar of 102, 112, 202 

sulphate 102 



410 



INDEX 



Lead — Continued. 

sulphide 68, 180 

White 113 

Leadbetter's Metalined rubber.. 130 

Leather, Cooley's artifical 102 

Leatherine 128 

Leatheroid 149 

Leatherubber compound 128 

Lemon oil 219 

Leonard's substitute 128 

Lessnenn and Weinkopf's for- 
mula 251 

Leva's drying process 46 

Liberian rubber 20 

Liconite 128 

Ligroin 240 

Lime 49,102 

juice 49 

Phosphate of 94 

Limeite 129 

Lini gum 165 

Linoxin 129 

Linseed oil 220 

Manganated 221 

Linum usitatissimum 220 

Liquid rubber 131 

Liquor of flint 202 

Litharge 103 

Lithargrite 103 

Lithographic varnish 220 

Lithopone (lithophone) 104, 188 

Lithro-carbon 165 

Little known rubbers 32 

Liver of sulphur 67 

Liverpool pressed rubber 18 

Loanda rubber 23 

Loango rubber 21, 23 

Lombiro rubber 24 

Lomi ball rubber 21 

Lopori rubber 22 

Loranthus rubber 39 

Lucas's gutta-percha compound. 391 
Luff. B. D. W., on synthetic rub- 
ber 269 

Luffs celluloid rubber 129 

Lugo 129 

rubber 129 

Lump rubber, African 18 

Luvituku rubber 22 

McCartney's reclaiming process 295 

Maboa gum 39 

Machacon juice 49 

Machines, Coagulating 50 

Beta separator 50 

Coutinho's 50 

DaCosta's 51 

Danin's 50 



Machines— Continued. 

Van den Kerckhove's 

fumero 51 

Wickham's 51 

Macintosh's gutta-percha com- 
pound 388 

Mackintoshes, Manufacture of.. 364 

MacMahon's Maponite 129 

Macwarrieballi gum 39 

Madagascar rubber 24 

Black 24 

Pinky 24 

Madanite 129 

Madeira rubber 12 

Magnesia, Heavy calcined 104 

Light calcined 104 

Maize oil 215 

Majunga rubber 24 

Brown cure 24 

niggers 24 

Unripe 24 

Malaya rubber 29 

Male rubber 42 

Mana 38 

Manaos rubber 12 

Mandarnva rubber 39 

Mangegatu gum 39 

Mangabeira rubber 16 

Manga-ice rubber 39 

Manganated linseed oil 221 

Manganese, Destruction of rub- 
ber by 105 

Peroxide 104 

Manihot dichotoma 16 

Glasiovii 16 

Manila gum 166 

Manjak 166 

Manoh twist rubber 20 

Manufacture of rubber goods... 351 

Maponite 129 

Marble flour 105 

Marcy*s rubber cure 55, 56, 57 

Marks' reclaiming process . . .294, 298 

Marloid 149 

Massaranduba rubber 39 

Massicot 105 

Mastic 166 

Matthew's process for colored de- 
signs on proofed 

fabrics 249 

Matto Grosso rubber 13 

Mayall's reclaiming process 295 

tape insulation 108 

Mayumba rubber 21 

Mechanical rubber goods, Analy- 
sis of 315 

Compounds for 355 

Manufacture of 354 



INDEX 



411 



Medium Para rubber 11 

Menthol 166 

Metalined .rubber 130 

Metals, Attaching rubber to.... 259 
on rubber, Action of.... 262 

Methane rubber solvent 239 

Mexican lac 171 

plantation rubber 31 

rubber IS 

Meyer's rubber cure 58 

Mica 105 

Micanite 149 

Milk of sulphur 68 

Milling rubber 353 

Mimo-tannic acid 202 

Mimusops balata 398 

Mineral india rubber asphalt . . . 166 

lac 153 

oil, Russian 225 

rubber 130 

tallow 166 

wax 167 

wool 105 

Minium 106 

Mirbane oil 221 

Miscellaneous processes 247 

Mitchell's reclaiming process... 294 

Mixing rubber 353 

Molded rubber goods, Compounds 370 

Manufacture of 369 

Mollendo rubber , . 13 

Molybdenum blue 181 

Mongalla rubber 22 

Montpellier, Analysis of gutta- 
percha by 393 

Morat white 188 

Morgan's Ce-re-gum 144 

Moroccoline 131 

Morondava rubber 24 

Mosley's process for ornament- 
ing proofed fabrics 251 

Mossamedes rubber 23 

Mt. Prospect Laboratory methods 
of analysis of vul- 
canized rubber . . . 329 

Moudan white 188 

Mountain flour 106 

milk 99 

Mowbray, Preservation of rub- 
ber goods by 258 

Mozambique rubber 23 

Mudar gum 39 

Mule gum 43 

Mulholland's insulation com- 
pound 107 

Mullee's rubber cure 59 

Muriate of ammonia 202 

Muriatic acid 202 



Murphy's rubber cure 58 

reclaiming process .... 298 

Musa paradisiaca 34 

sapientum 34 

Musa Gum 40 

Mustard oil 221 

Myrrh 167 

Nagel's patent Con-current rub- 
ber 122 

Namaqualand rubber 40 

Nantusi 68 

Naphtha 239 

Boiling points of 241 

Bone 237 

Coal-tar 240 

Pentane 241 

Petroleum 240 

Benzine 240 

Gasoline 240 

Ligroin 240 

Rhigolene 240 

specific gravity of 

(table) 241 

Naphthalene 239 

National Board of Fire Under- 
writers' Labora- 
tories' methods of 

analysis 321 

Natural pitch 167 

Nature of india rubber 7 

Neatsfoot oil 221 

Neen rubber 40 

Negroheads 11 

Neilson's reclaiming process 298 

New Caledonia rubber 27 

Newbrough's and Fagan's rubber 

cure 64 

Newbrough's rubber cure 57 

Newmastic 267 

Nicaragua rubber 14 

Nickels' rubber cure 60 

Niger rubber 21 

Nigeria rubbers 21 

Niggers, African rubber 19 

Sierra Leone 20 

Nigrite 149 

Nigrum Elasticum 131 

Nipa fruticans 49 

sa lt 49 

Nitrate, Lead ' .' .' .' .' .' .' .' .' ! '.'. .' .' '. .' .' .' .' 202 

Nitric acid 202 

Nitrobenzene 221 

Nitrobenzol 221 

Nitrocellulose . 149 

Notion rubber trade, Compounds 

for 374 

manufacture 374 



412 



INDEX 



Novelty rubber substitute 131 

Nut-gall 203 

Nuts, African rubber 18 



Obach, Analysis of gutta-percha 

by 397 

composition of gutta- 
percha resins 397 

Ocotillo rubber 40 

Oceanica rubber 27 

Ocher, Red 185 

Yellow 193 

Ohmlac 132 

Oil, Blown 213 

Camphor 214 

Caoutchouc 214 

Castor 214 

Cod-liver 214 

Colza 215, 224 

Consolidated 215 

Corn 215 

Cottonseed 215 

Creosote 215 

Derry's waterproof har- 
ness 226 

Dippel's 237 

Eucalyptus 215 

Fish 216 

Fusel 231 

Kerosene 217 

Lallemantia 218 

Lard 219 

Lavender 219 

Lemon 219 

Linseed 219 

Maize 215 

Manganated linseed . . . 221 

Mirbane 221 

Mustard 221 

Neatsfoot 221 

of vitriol 203 

Olive 222 

Origanum 226 

Orris 222 

Palm 222 

Congo 223 

Lagos 223 

White 223 

Peppermint 223 

Petroleum 224 

Pine 244 

Poppyseed 225 

Rapeseed 215,225 

Rock 224 

Rosemary 225 

Rosin 225, 244 

Russian mineral 225 



Oil — Continued 

Shale 225 

Tar 226 

Thyme 226 

Turpentine 226, 245 

Vulcanized 227 

Walnut 227 

White drying 227 

Rangoon 224 

Wormwood 227 

Oils used in rubber compounds. 213 

Okonite 132 

Old Calabar rubber 20, 21 

Oleargum 222 

Oleic acid 203 

Oleo resins 167 

Oleum white 188 

Olibanum gum 167 

Olive oil 221 

Olivier's ultra violet rays cure.. 61 

Ols son's Zackingummi 140 

Optimum cure 71, 345 

Orange ball rubber 23 

mineral 106 

vermilion 185 

Orinoco rubber 13 

Orris oil 222 

Orr's white 189 

Ossein 106 

Ostromislensky's theory of vul- 
canization 275 

Oxalic acid 203 

Oxidation and vulcanization, Ve- 
locity of 285 

Oximony 185 

Oxolin 132 

Oxydases in crude rubber 52 

Oysters, African 19 

Ozocerine 167 

Ozocerite 168 

Pagodite 106 

Pala gum 40 

Palm oil 222 

Congo 223 

Lagos 223 

White 223 

Palo Amarillo gum 41 

Colorado 41 

Panama rubber 15 

Pantasote 149 

Papaver somniferum 225 

Para rubber 10 

Paraffin wax 168, 223 

Paragol 132 

Paris black 180 

white 107 

Parkesine 132 



INDEX 



413 



Parkes's gutta-percha compound 391 

surface colors 247 

Parmelee's rubber cure 57 

Parthenium argentatum 17 

Passmore's reclaiming process.. 298 

Paste rubbers, African 18 

Pau rubber 39 

Payena 43 

Payen's analysis of gutta-percha 397 

lead acetate patent 101 

Pectous rubber 308 

Pedryoid 133 

Pegamoid 149 

Penang rubber 25 

Pensa's rubber 133 

Pentane 241 

Pentasulphide, Antimony 68 

Penther's reclaiming process . . . 298 

Peppermint oil 223 

Perchoid 133 

Permanent white 93, 107 

Pernambuco rubber 16 

Peroxide, Iron 185 

Hydrogen 202 

substitutes 133 

Peruvian rubber 13 

Peterson's reclaiming process . . . 298 

Petrifite 106 

Petrolatum 223 

Petroleum jelly 224 

naphtha 240 

oil 224 

Rangoon white 224 

solvents 241 

Phenol 204 

Phosphate of sodium 209 

Phosphorus 106 

Physical testing of rubber goods, 

302, 337 
Air brake and signal hose 343 

Bursting tests of 345 

Friction test of 344 

Porosity test of 344 

Stretching test of cover 

and tube of 344 

Tensile strength of 
tube and cover of 344 

Test specimen of 343 

Defects of test pieces for 343 

Set in 342 

Bar test pieces for . . . 343 
Ring test pieces for... 343 

Standard methods of 338 

Temperature 339 

Tensile strength 339 

Time 339 

Tensile strength deter- 
mination 341 

across the seam 342 



Physical testing of rubber 

good s — Co ntinued. 
Tensile strength — Continued. 

Apparatus for 341 

bar test pieces for, 

Marking 341 

Measurement of 341 

Breaking 341 

breaking point, Elon- 
gation at 342 

Grips 341 

ring test pieces.. 341, 342 
ring test pieces, Meas- 
urements of 341 

test pieces, Preparation of 339 

Averages 338 

Elongation 339 

Friction 340 

Sampling 338 

Set 339 

Pickeum gum 41 

substitute . 133 

Picradenia floribunda utilis 41 

Pigments for coloring rubber... 176 

Pine oil 244 

Pinus maritima 175 

\palustris 175 

Sylvestris 244 

Pioneer mineral rubber 131 

Pipe clay 107 

Pistacia lentiscus 175 

Pitch 169 

Black 158 

Burgundy 158 

Coalite 160 

Jews 155 

Natural 167 

Stearine 173 

Vegetable 175 

Pithecolobium bigeminum 207 

Plantation rubber 27 

Forms of 31 

Biscuits 29 

Block 30 

Crepe 29 

Flake 30 

Lace 30 

Scrap 30 

Sheets 29 

Worm 30 

Hevea, Optimum cure of 71 

Market names of 30 

Amber crepe 30 

Brown crepe 30 

Ceara 31 

Central American 31 

Ceylon Castilloa 31 

Colombo scrap 31 



414 



INDEX 



Plantation rubber — Continued. 
Market names of — Con. 

Congo 31 

First latex crepe 30 

Guayaquil Castilloa .. 31 

Java Castilloa 31 

Mexican 31 

Rambong 31 

Smoked Sheet, plain 
standard quality. . 31 
ribbed standard 

quality 31 

Tobago 31 

Trinidad 31 

Uganda 31 

Unsmoke(d Sheet, 
standard quality.. 31 

West Indies 31 

World's Annual produc- 
tion of (table).... 28 

Plaster of Paris 107 

Plasters, Compounds for 375 

Manufacture of 375 

Plasticon 150 

Plastite 150 

Plumbagine 108 

Plumbago 108 

Ponolith 189 

Pontianak rubber 26 

Pressed 26 

Refined 26 

Poppenhusen reclaiming process. 295 

Poppyseed oil 225 

Portland cement 108 

Potash 204 

caustic 205 

Potassium acid tartrate 204 

arsenate 204 

bichromate 204 

bisulphate 204 

carbonate 204 

cyanide 205 

hydroxide 205 

permanganate 205 

Potato celluloid 150 

Pouckpong gum 42 

Powdered coal 109 

Pozelina 49 

Pratt Vulcabeston 152 

Preserving rubber goods, Proc- 
esses for 257 

Benton's 258 

Elworthy's 258 

Kreusler and Bude's 257 

Mowbray's 258 

Trueman's 258 

Truss' 259 

under water 257 

Zingler's 259 



Presspahm 150 

Pressure cure , 62 

Price (American) reclaiming 

process 298 

(English) r e c la i ming 

process 298 

Prince's metallic paint 185 

Printing on inflatable rubber 

films 248 

Proofed fabrics, Compounds for. 364 

Manufacture of 364 

Ornamenting 248 

Properties in rubber, Relation- 
ship of mechanical 

to chemical 345 

Depolymerization 346 

Optimum cure 345 

Stress-strain type curve. 348 

Propylene chloride 244 

Proto-chloride, Sulphur 68 

Prussian blue 181 

red 185 

Pumice 109 

Puncture fluids and tire fillers . . 266 
Campbell and Cushman's 266 

Cellazote 267 

Cyco 266 

Dow's 266 

Elastes 266 

Everlastic 266 

Fagioli's 266 

Frankenburg's 266 

Inrig 267 

Newmastic 267 

Puncture Closer 267 

Roland's 267 

Rubber foam 267 

Rubberine 268 

Scott's 268 

Suber's 268 

Tire Life 268 

Purcellite 133 

Purub 49 

Purus rubber 12 

Puzzolana 110 

Pyroxylin 150 

P. F. U. gum 41 

Quercus infectonia 203 

Quicklime 205 

Quinn's rubber 134 

Quittah niggers rubber 20 

Rambong plantation rubber 31 

Rangoon rubber 25 

Rapeseed oil 215, 225 

Rate of cure of plantation Para 

rubber 73, 311 



INDEX 



415 



Rate of cure of plantation Para 
rubber, — Continued. 
Eaton and Grantham on 
causes of variabil- 
ity in 71, 73 

Analytical work of 75 

Conclusions of 74, 75 

Experiments of 73, 75 

Nitrogen content and 75 

Summary on 77 

Schidrowitz on 72 

Rathite 134 

Raven mineral rubber 131 

Raymond's rubber cure 61 

Reagents for rubber analysis . . . 315 

Reclaimed rubber . 290 

U. S. annual production 

of 290 

Reclaiming rubber, Processes for 292 

Alexander's 295 

Anderson's 295 

Baschnagel's 293 

Basle's 296 

Beylikgy's 295 

Bourn's 294 

Brimmer's 296 

Chautard's 296 

Chemical 291 

Clapp's 293 

Cliffs 296 

Durvez's 296 

Eves's 296 

Faure's 294 

French 296 

Gilbert-Besaw's 296 

Gregory and Thorn's . . . 297 

Gubbin's 297 

Hall's 293 

Hayward's 294 

Heinzerling's 294, 297 

Heyl-Dia's 297 

Hyatt and Penn's 297 

Karavodine's 297 

Kessler's 297 

Kittel's 297 

Koener's 297 

Koneman's 297 

McCartney's 295 

Machinery used for 292 

Marks' 294, 298 

Mayall's 295 

Mechanical 291 

Mitchell's 294 

Murphy's 298 

Neilson's 298 

Passmore's 298 

Penther's 298 

Peterson's 298 

Poppenhusen's 295 



Reclaiming rubber — Continued. 

Price's (American) 298 

(English) 298 

Roux's 298 

salt 206 

Simond's 295 

Spence's 299 

Steenstrup's 298 

Theilgaard's 298 

Torstrick's 294 

Wheeler's 298 

Zuhl's 299 

Red Antimony sulphide 66 

Antimony crimson sul- 
phide 184 

chalk 109 

hematite 185 

Indian 185 

Iron oxide 185 

Peroxide 185 

lead 110 

ocher 185 

orange vermilion 185 

pigments for rubber 184 

Prince's metallic 185 

Prussian 185 

Venetian 185 

Reid's Velvril 138 

Remanso rubber 16 

Rennet 206 

Repin's tong oil substitute 137 

Resin, Amber 154 

Jelutong 164 

Sludge oil 172 

Turpentine 175 

Resinolines 134 

Resins 153, 170 

Oleo 167 

Rubber 229, 308 

Retinasphalt 170 

Retinite 170 

Rhea gum 134 

Rhigolene .240, 241, 244 

Rice rubber 134 

Rider's gutta-percha compound.. 391 

rubber cure 58 

Riviere's Elasteine 123 

Rock oil 224 

Roland's puncture compound 267 

Rosaline 134 

Rosemary oil , 225 

Rosenstein's method for total 
sulphur in vulcan- 
ized rubber 331 

Rosin 170 

oil 225, 244 

Ross's white 189 

Rostaing's gutta-percha com- 
pound 391 



416 



INDEX 



Rotten stone 110 

Rouen white 189 

Roux reclaiming process 298 

Rubber, Action of metals on 262 

Adhesive principle of 

crude 8 

asphalt 135 

Calendering 353 

cements 372 

Chemical formula of. .8, 271 
Coefficient of vulcaniza- 
tion and the state 

of cure of 347 

colors, Requirements for 249 
Deodorization of ...116, 256 

Electroplating on 248 

Embossing of 248 

flux 135 

foam 267 

goods, Physical testing of 337 

grades, Crude . 10 

Harries formula for 271 

Impregnating 251 

Insoluble matter in .... 309 

latex 8 

Adulteration of 34 

Analysis of Hevea, 44, 266 

makers' white 189 

manufacture 354 

Divisions in 354 

Boots and shoes 357 

Cement 372 

Dental and stamp 

gum 373 

Druggists', station- 
ers' and surgical 

sundries 361 

Hard rubber 371 

Insulated wire 368 

Mackintoshes, proof- 
ing and carriage 

cloth 364 

Mechanical goods . . 354 

Mold work 369 

Notions 374 

Plasters 375 

TireS 366 

Primary processes in. 351 

Calendering 353 

Drying 352 

Milling 353 

Spreading 354 

Washing 351 

"Nervy" principle in.. 8, 308 
Nitrogenous substances 

in 309 

Oil substitutes for 117 

Analyses of . (table) . . 118 
Optimum, cure of 346 



Rubber — Continued. 

Physical properties of.. 7 

pigments 176 

Preserving goods 257 

scrap 292 

Shrinkage of 263 

Solubility of (tables), 

228, 229 

resins (tables) 229 

solvents 230 

Sources of 7 

Specific gravity of. .265, 349 

Synthetic .269, 274 

tree, Male 42 

"Type" curve of crude.. 348 

Uniting metals to 259 

Valuation of crude 303 

velvet 135 

Rubberaid 135 

Rubberic 135 

Rubberine 268 

Rubberite 135 

Ruberine 135 

Ruberoid 135 

Rub-hide 136 

Russian mineral oil 225 

Sal ammoniac 206 

soda 206 

Saleratus 206 

Salicylic acid 206 

Salol, vulcanized rubber solvent. 329 
Salt 49, 206 

Reclaiming 206 

Saltpeter 206 

Salt-pond rubber 20 

Sandarac gum 171 

Sankuru 22 

Santos rubber 16 

Sapium biglandulosum 42 

tolimense 15 

Sapotacece 377 

Sarawak 26 

Sarco 136 

Sarua rubber 41 

Satin gloss black 180 

Saxon blue 181 

Schidrowitz, examination of crude 

rubber 307 

and Goldsborough on co- 
efficient of vulcan- 
ization and state 
of cure 348 

stress strain type curves 348 

Scott's puncture fluid 268 

Seedlac 171 

Seiba gum 4 .41, 42 



INDEX 



417 



Selenium 110 

Senegal gum 171 

Sleringuina 49 

Sernamby Para rubber 10, 11 

Shale, Argillaceous red 90 

oil .. 225 

spirit 244 

Sharpe, Analysis of gutta-percha 

by 397 

Composition of gutta- 
percha by 397 

Shea butter 38 

Shellac 171 

Shepard's gutta-percha compound 390 

Showerproofing 251 

American 252, 253 

Cohuru's 255 

Cravenette 251 

English 253 

Forster's 254 

Frankenburg's 255 

German 252, 254 

Kyanized 254 

Smith's porous fabric... 255 
Shrinkage of crude rubber 

(tables) 263, 264 

Sierra Leone rubbers 20 

Silex 110 

Silica 110 

Silicate, Carbon black 180 

Cotton 110 

Silicon fluoride 206 

Silky Assinee rubber :. 20 

Siluminite 150 

Simond's reclaiming process 295 

Simpson's rubber cure 57 

Sinapis alba 221 

nigra 221 

Size 172 

Slag wool 110 

Slaked lime 110 

Slate 110 

Sludge oil resins 172 

Smalts 182 

Analysis of (table) 182 

Smith's, Thos., Theskelon cement 137 
porous fabric shower- 
proofing 255 

Willoughby, gutta-per- 
cha compound. 152, 387 

Soap 50, 206 

bark 207 

Castile 207 

Resin 207 

substitutes 136 

Soapstone Ill 

Soda 207 

Caustic .. 209 

Sal 206 



Sodium biborate 207 

bisulphite 208 

carbonate 208 

chloride 208 

hydroxide 209 

hyposulphite 209 

phosphate 209 

silicate 210 

sulphate 210 

tungstate 210 

Solicum 136 

Solubility of rubber (tables). 228, 229 
of rubber resins (table) . 229 

Soluble glass 210 

Solvent, Chute's rubber resin 236 

Gottsch's vulcanized rub- 
ber 329 

Twiss' vulcanized rub- 
ber 328 

Solvents 228 

Methane 239 

Petroleum 241 

Rubber 230 

Vulcanized rubber 328 

Sorel's compound 103, 151 

Soudan rubber 19 

Spanish white 189 

"Special" brand zinc oxide 190 

Specific gravity, Determination of 350 
in rubber compounding. . 349 

of rubber 265 

of petroleum naphtha 

(table) 241 

Specification, Thirty per cent. 
Hevea insulation 

compound 333 

Spence, color in crude rubber . . 52 
"On the Relationship of 
Mechanical to 
Chemical Proper- 
ties" 345 

oxydases in crude rub- 
ber 52 

reclaiming process 299 

Spermaceti 173 

Spill's gutta-percha compound.. 389 

Spindle rubber 23 

Spirits of turpentine 245 

of wine 50 

Wood 246 

Spreading rubber 354 

Spruce gum 173 

St. George turpentine rubber 138 

Stabilit 151 

Starch Ill 

Stearine, 173, 226 

pitch 173 

Steenstrup's reclaiming process. 298 



418 



INDEX 



Stevens, coefficient of vulcaniza- 
tion 347 

rate of cure 79 

Stick rubber 23 

Sticklac 171, 173 

Stockholm tar 173 

Storax, Balsam of 156 

Straits rubber 29 

Strasburg turpentine 158 

Suber's filler 268 

Sublimed lead Ill 

Submarine cables, Insulation of. 387 

Substitute, Blandy's 120 

Brown's hard rubber 143 

Carbon bisulphide 234 

Dankwerth's 122 

De Pont's , . 145 

Fayolles' 124 

Franklin 125 

German black 120 

Griscom's 125 

Harmer's 126 

Jones's 127 

Moroccoline 131 

Nature and use of 117 

Nigrum Elasticum 131 

Novelty rubber 1 131 

Ohmlac 132 

Paragol 132 

Pedryoid 133 

Perchoid 133 

Peroxide 133 

Pickeum 133 

Purcellite 133 

Resinolines 134 

Russian 136 

Soap 136 

Tong oil 137 

Wichmann's 139 

Wolfert's 139 

Sugar of lead 112, 202 

Sulo 136 

Sulphate, Sodium 210 

Sulphide, Lead 68 

Zinc 68 

Sulphur 69 

Balsam of 69, 156 

bath cure 63 

chloride 65 

fumes 50 

Honeycomb 67 

Liver of 68 

lotum 69 

Milk of 68 

Sulphuret, Antimony 66 

Sulphuric acid 210 

Sumatra rubber 29 

Surface colors _ 247 

printing 247 



Susu-poko gum 41 

Synthetic rubber 269 

Available sources of 273 

Butanes 272 

Early investigations on. 269 

dimethyl butanes 272 

History of 269, 270 

Isoprene 271, 272 

Practical utility of 273 

Production of 270 

Tabbyite 136 

Tabemcemontana Thurstoni .... 41 

Talaing rubber 41 

Talc Ill 

Talite 112 

Tallow 226 

Mineral 166 

Talotalo gum 41 

Tamatave rubber 24 

Pinky 24 

Tannic acid 211 

Tannin 211 

Tar 174 

Birch bark 157 

Candle 159 

oil 226 

Stockholm 173 

Tarpaulin compound 102 

Tartaric acid 211 

Tava rubber 23 

Taylor's Purcellite 133 

Terra-verte 183 

Analysis of 184 

Tetrachloride, Carbon 235, 244 

Tetrachlormethenie benzene sub- 
stitute 244 

Texoderm 151 

Textiloid 137 

Theilgaard's reclaiming process. 298 

Thenard's blue 182 

Theskelon cement 137 

Thimbles, African 18 

Thion 245 

Thomas's rubber cure 56 

Thus, Gum 174 

Thyme oil 226 

Thymus vulgaris 226 

Tin oxide 113 

Tire Life 268 

Tires, Compound for 367 

Manufacture of 366 

Tirucalli gum 42 

Tobago plantation rubber 31 

Togoland rubber 21 

Tolu balsam 174 

Toluene 245 



INDEX 



419 



Toluol 245 

Tong oil substitutes 137 

Tongues, African 19 

Toonu gum . 42 

Torres' system of coagulation. .. 50 
Torstrick's reclaiming process.. 294 

Touchpong gum 42 

Tragacanth, Gum 174 

Tragasol, Gum 174 

Tremenol 137 

Trinidad asphalt 174 

plantation rubber 31 

Triple compound, Goodyear's. . . 113 

Tripoli 112 

Trotter's rubber cure 55 

Troye's white , 189 

Trueman, preservation of rubber 

goods 258 

Truss, preservation of rubber 

goods 259 

Tu Chung rubber 42 

Tungstate, Sodium 210 

Tungstic acid 212 

Tuno gum 42 

Tunu gum 43 

Turnbull's rubber paint 137 

Turner's yellow 102 

Turpentine 175, 226 

Bordeaux 175 

China 175 

Crude 245 

Oil of 226, 245 

resin 175 

rubber 138 

Spirits of 245 

Strasburg 158 

Venice 175 

Turpin's hydrocarbon rubber . . . 126 

Tuxpam strip rubber 15 

Twiss' solvent for vulcanized 

rubber 328 

Twist, African 19 

Sierra Leone 20 

Tyer's white rubber 189 

Types of Plantation Para 30 

Tyre-lith 112 

Uganda rubber 23 

plantation 31 

Uele rubber 22 

Ultramarine blue 182 

analyses of (tables) 182 

Green 184 

Uniting rubber to metals, Proc- 
esses for 259 

Adam's 260 

Daft's 261 



Uniting rubber to metals, Proc- 
esses for — Continued. 

Garrity and Avery's 260 

Hall's 260 

melting 259 

solid tires 260 

Upper Congo rubber 22 

Upriver rubber 12 

Uranium sulphide 180 

Vapor cure 54 

Variability in rate of cure, 

Causes of 71 

Varnish, Boot and shoe 361 

Lithographic 220 

Vaseline 226 

Vegetable pitch 175 

Vegetaline 151 

Velvril 138 

Venetian red 185 

Vermilion 186 

Vesuvian white 70 

Virgin rubber 15 

Viscoid 151 

Viscose 151 

Viscosity of crude rubber 311 

Vitriol, Oil of 203 

Vitrite 151 

Volenite 138 

Voltax 138 

Voltit 138 

Vorite 139 

Vulcabeston 152 

Vulcanina 139 

Vulcanine 70, 139 

Vulcanization, Coefficient of 311 

Gutta-percha , 389 

Ostromislensky's theory 

of 281 

process of, Ayling's .... 58 

Banigan's 57 

Bernstein's 61, 62 

Caulbry's 60 

Cold 54, 59 

Dieffenbach's 56 

Eaton's, A. K 56 

Electric 63 

Elmer's 59 

Falke and Richards'.. 56 

Garnier's 60 

Gerard's 68 

Goodyear's, Charles . . 55 

Hancock's, Charles ... 60 

Harris' 56 

Havermann's 58 

Helbronner and Bern- 
stein's 61, 62 

Helm's 58, 65 



420 



INDEX 



Vulcanization — Continued. 

process of — Continued. 

Henri's 61 

Hot 55 

Joselyn's 56 

Marcy's 55,56, 57 

Meyer's ■. 58 

Mullee's 59 

Murphy's 58 

Newbrough and Fa- 

gan's 64 

Newbrough's 57 

Nickels' 60 

Olivier's 61 

Ostromislensky's 275 

Parkes', Alex 59 

Parmelee's 57 

Pressure cure 62 

Raymond's 61 

Rider's 58 

Simpson's 57 

Sulphur bath 63 

Thomas' 56 

Trotter's 55 

Ultra-violet rays 61 

Vapor 54, 59 

Willman's 57 

without sulphur 275 

Accelerators for 282 

Agents for 287 

benzoyl peroxide. .283, 284 

mechanism of 280 

n i t r o-c ompounds 

(table) 288 

organic p e r o x ides 

(table) 289 

Patents for 285, 287 

peroxides 282 

trinitrobenzene ...277, 278 

Vulcanized rubber analysis 312 

Aniline method for min- 
eral fillers in 323 

Bureau of Stand ards' 

methods for.. 312, 314 
insulation, 30 per cent. 

Para 318 

acetone extract 319 

alcoholic potash ex- 
tract 320 

ash 320 

calculations 320 

chloroform extract.. 320 

free sulphur 319 

general 318 

total sulphur 320 

unsaponifiable mat- 
ter .. 319 

waxy hydrocarbons 319 
mechanical goods 315 



Vulcanized rubber analysis — Con. 

acetone extract 315 

alcoholic-potash ex- 
tract 318 

ash 317 

barytes 317 

calculations 318 

free sulphur 316 

specific gravity 318 

sulphur of ash 317 

total sulphur 316 

outline plan 312 

preparation of samples 314 

grinding 314 

hard rubber 315 

soft rubber 314 

reagents 315 

acetone 315 

alcoholic potash .... 315 
barium c h 1 o r ide 

solution . . . . 315 

fusion mixture 315 

nitric acid-bromine. 315 

remarks on 312 

acetone extract 312 

alcoholic-potash ex- 
tract 314 

ash and sulphur in 

ash 313 

barytes 313 

chloroform extract.. 314 

free sulphur 313 

rubber 313 

specific gravity 314 

total sulphur 313 

Electrolytic methods for 332 

Lead 332 

Zinc 332 

Joint Rubber Insulation 
Committee's meth- 
ods for 321 

calculation 321 

outline plan (table) . . . 322 
Mt. Prospect Laboratory 

methods for 329 

alcoholic-p o t ash ex- 
tract 330 

free sulphur 329 

mineral fillers 329 

rubber by weight 330 

by volume 330 

Rubber by wet combus- 
tion 324 

Solvents for 328, 329 

Sulphate sulphur method 328 
Sulphide sulphur meth- 
od 326, 327 

Vulcanizing ingredients 63 

pressures (table) 70 



INDEX 



421 



Vulcanizing ingredients — Continued. 

processes 54 

temperatures (tables) . . 70 

Vulcole 70 

Vulcoleine 246 

Walnut oil 227 

Wamba rubber 23 

Washers, Unvulcanized packing. 138 

Washing rubber 351 

Waste rubber, Grades of 291, 293 

Sources of 293 

Wax, Ant 40 

Bees 156 

Candelitta 159 

Carnauba 159 

Earth 161 

Japan 217 

Mineral 167 

Paraffin 168, 223 

Weber, Dr. C. O., analysis of 

vulcanized rubber. 312 
cellulose compound .... 152 
Wesson and Knorr, rubber by 

wet combustion . . 324 

West Indian rubber 16 

Wet heat cure 54 

Whalebone, Artificial 141 

Whaleite 139 

Wheat flour 113 

rubber 139 

Wheeler's reclaiming process... 298 

White, Barium 187 

Beckton 187 

Blanc fixe 186 

Bougival 187 

Calamine 187 

Charlton 187 

Chinese ...,, 188 

Constant white 186 

Fard's Spanish 188 

Fulton 188 

Griffith's 188 

Kremnitz 188 

lead 113 

Lithopone (lithophone) . 188 

Morat 188 

Moudan 188 

Oleum 189 

Orr's 189 

pigments for rubber 186 

Ponolith 189 

Ross's 189 

Rouen 189 

Rubber Makers' ........ 189 

Spanish 189 

Troye's 189 



White — Continued. 

vitriol 114 

Zinc borate 187 

carbonate 189 

oxide 189 

sulphide 191 

Whiting 113 

Wichmann's substitute 139 

Wickham's machine 51 

Willman's rubber cure 57 

Winthrop gum 139 

Witherite 114 

Wolfert's substitute 139 

Wood ashes 50 

spirit 246 

Woodite 139 

Wormwood oil 227 

Wray's gutta-percha compound, 

152, 387 



Xanthorkho2A, Arborea 153 

Australis 153 

gum 175 

Hastilis 153 

Xelton 152 

Xingu rubber 11 

Xylene 246 

Xyloidin 175 

Xylol 246 

Xylonite 152, 175 

"XX" brand zinc oxide 190 

Yale blue 183 

Yellow, Antimony golden sul- 
phide 191 

Arsenic 192 

Aureolin 192 

Barberry 192 

Cadmium 192 

Carsel 102 

Chrome 193 

Cobalt 193 

Dutch pink 193 

Gamboge 193 

gutta 43 

ocher 193 

pigments for rubber 191 

Turner's 102 

Zinc 193 

Zackingummi 140 

Zea mays 215 

Zinc borate , 187 

carbonate 189 



422 



INDEX 



Zinc — Continued. 

chloride 212 

iodide 212 

oxide 114, 189 

"Green Seal" brand... 190 
"Red Seal" brand.... 190 

"Special" brand 190 

"White Seal" brand.. 190 

"XX" brand 190 

sulphate 114 



Zinc — Continued. 

sulphide 69, 114, 191 

white 191 

yellow 193 

Zingler's Dermatine compound.. 123 
preservation of rubber 

goods 259 

Zinsser's barrel lining 140 

Zuhl's reclaiming process 299 

Zylonite 175 



ADVERTISEMENTS 



For Index see page 5 



ADVER TI SEMEN TS 



GRANULATED M.R.X. 

Economy of Cost and Stronger Rubber 

Besides 

Ease of handling 

Accuracy of 
weighing 

Saving of waste 

there is 

the further great 

advantage of 

Quick Mixing 

The granulated 
particles are ab- 
sorbed so quickly 
by the rubber and 
compounds, and so 
assist the process, 
that mixing is com- 
pleted in about half 
the usual time. 

This gets the rub- 
ber off the mill in 
time to save much of 
the disruption of th e 
fibres which detracts 
so much from the 
strength of the gum. 

By using Granulated M.R.X. you save time and get 
stronger rubber. Samples and price on application. 

Standard Emarex Company 




208 South La Salle St. 



CHICAGO, ILL. 



AD VER T I SEMEN TS 



RUBBER 

Colors and Compounds 



Antimony 

Golden and Crimson 

Blanc Fixe 
Blue 

Chrome Green 
Chrome Yellow 
Indian Red 



Magnesia Carbonate 

Magnesia Calcined 

Ochre 

Vermilion 

Zinc Oxide 

Zinc Yellow 



Etc. 



Reichard-Coulston, Inc. 

C 303 Fifth Avenue 
New York City New York 



ADVERTISEMENTS 



BUFFALO 



BRANDS 



RECLAIMED 
RUBBER 



The Result of 34 Years Con- 
sistent Progress and Development 

U. S. RUBBER RECLAIMING CO., Inc. 

20 West 60th St., (Near Broadway) NEW YORK 



INDEX OF ADVERTISERS 

Acushnet Process Co 12 

Aluminum Flake Co., The 28 

Astlett, H. A. & Co 7 

Binney & Smith Co 16 

Birmingham Iron Foundry 36 

Boston Yarn Co 29 

Buffalo Foundry & Machine Co 33 

Butcher, L. H. Co., Inc • 44 

Cabot, Samuel, Inc Inside Front Cover 

Canfield Oil Co., The 25 

Carter Bell Manufacturing Co., The 25 

Connecticut Mills Co 30 

Continental Rubber Co. of New York 12 

Consulting Co., The .- 40 

Cutler, David A 38 

Day, J. H. Co., The 36 

Eagle-Pitcher Lead Co., The 18 

Farrel Foundry & Machine Co 34 

Frazar & Co Opposite Back Cover 

Henderson, F. R. & Co 8 

Hoggson & Pettis Manufacturing Co., The 35 

India Rubber Publishing Co., The 10, 15, 17, 28, 37 

Katzenbach & Bullock Co 41 

Loewenthal, R. M. & Co 6 

Manhasset Manufacturing Co 32 

Maywald, Frederick J., F. C. S 40 

Obalski, X. W., & Co 9 

Philadelphia Rubber Works Co • 13 

Rare Metal Products Co 27 

Raven Mining Co. of Utah 19 

Reichard-Coulston, Inc., 3 

Roessler & Hasslacher Chemical Co., The 26 

Scheel, William H 28 

Schrader's, A. Son, Inc ,. 42, 43 

Scott, Henry L. & Co Inside Back Cover 

Seaver & Co 20 

Somerset Rubber Reclaiming Works 14 

Stamford Rubber Supply Co., The 21 

Standard Emarex Co 2 

Stresen-Reuter & Hancock, Inc 22 

Tagliabue, C. J. Manufacturing Co 32 

Taylor, Armitage & Co., Inc 31 

Typke & King, Ltd 27 

Tyson Brothers, Inc 23 

U. S. Rubber Reclaiming Co., Inc 4 

Waldo, E. M. & F Opposite Inside Front Cover 

Weber, Lothar E., Dr 39 

West, H. T. Co., Inc 24 

Westmoreland Chemical and Color Co., The 26 

Williams, C. K. & Co 26 

Wood, Charles E 11 



ADVERTISEMENTS 



R. M. LOEWENTHAL & CO. 

INCORPORATED 




Tire Scrap 
Exclusively 



As specialists in our line, we place 
at your disposal expert service based 
on years of "knowing how", and 
guarantees backed by reputation 



If You {?$} Auto Scrap We liffl It 



51 East 42nd Street 



New York 



ADVERTISEMENTS 



H. A. ASTLETT & CO. 



Importers of 



Crude Rubber 



WASHED AND REFINED 
PARAS CARRIED IN STOCK 



113-117 Pearl Street, - New York 



ADVER TI SEMEN TS 



F. R. Henderson & Co. 



Crude Rubber 



New York ■* - - Akron 



ADVERTISEMENTS 



SWEENEY & COMPANY, Inc. 
Crude Rubber 

Importers and Merchants 



59-61 Pearl Street 

Cable Address: 
'Sweneco" New York New York 



X. W. Obalski & Co., Inc. 



CRUDE RUBBER 



291-295 Broadway, New York City 



10 



ADVER T IS EM EN TS 



The Rubber Country of The Amazon 

By HENRY C. PEARSON, F.R.G.S. 

The most informing story of the Brazilian rubber centers ever 
written. 

It reflects intimate knowledge, based on years of study, and 
the observations and experiences during the writer's several visits 

to the Amazon country. 

After being a rubber man- 
ufacturer, and for 25 years a 
writer on rubber; after trav- 
eling, through the rubber- 
planting belt around the 
world, and visiting all the 
plantation centers of Mexico, 
Central America and the Far 
East, the author spent a win- 
ter in the country of the 
Amazon, leisurely traversing 
the course of that great river 
from Para to Manaos and 
beyond. 

He describes the country, 
its flora and fauna ; its peo- 
ple and their customs ; the 
rubber forests, the gatherer's 
life and methods, and the 
processes of tapping and co- 
agulating. He covers the 
upper Amazon and its tributaries and describes the rubber interests 
of Bolivia, Peru, Colombia, and of Acre — the richest rubber terri- 
tory in the world. 

In addition to this, the book deals with the various phases of 
planting, gathering and marketing of rubber, and will be found both 
a highly instructive and very entertaining narrative of a section in- 
timately known to few, but of great and increasing interest to many. 
Profusely Illustrated 




PRICE, $3.00 



PUBLISHED BY 



The India Rubber Publishing Company 

25 West 45th Street, New York 



ADVERTISEMENTS H 



CHARLES E. WOOD 

287 Broadway Corner Reade Street 

NEW YORK 

Telephone: Worth 5100-5107 
BROKER IN 

Crude Rubber, Balata 

Gutta Percha and 

Kindred Products 



Prompt Attention and Efficient Service 
to Buyer and Seller Alike 



AKRON OFFICE: Room 328 Hamilton Building 

Bell Phone 7007 Main 



12 ADVERTISEMENTS 



Continental Rubber Company of New York 
GUAYULE RUBBER 



Usual Good Quality 

20% Shrinkage: 

CIRCLE BRAND 

PARRA BRAND 



Washed and Dried 

Ready for 

Compounding: 

TRIANGLE BRAND 

DURO BRAND 



120 Broadway, New York 



Scientific Treatment 

of 

Crude Rubber 

and 

Reclaiming of Friction Scrap 

for 

The Trade 

ACUSHNET PROCESS CO. 

NEW BEDFORD, MASS. 



ADVERTISEMENTS 13 



THE PHILADELPHIA RUBBER WORKS 

COMPANY 

Manufacturer of 

RECLAIMED RUBBER 

of 

STANDARDIZED QUALITY 



NEW YORK: 

52 VANDERBILT AVE. 



PHILADELPHIA, PA. 

AKRON, OHIO LAND TITLE BLDG. 



14 ADVERTISEMENTS 



RECLAIMED RUBBER 

THAT HAS STOOD 
THE TEST FOR YEARS 



Special GRADES for the following TRADES. 

Insulated Wire 

Boot and Shoe 

Mechanical— Auto Tire 

Proofing 

Hard Rubber 



We will cheerfully furnish samples upon request 



Wl :-: 



SOMERSET RUBBER 
RECLAIMING WORKS 

New Brunswick, N. J. 

Factory — East Millstone, Somerset County, N. J. 

-■-- ' - --^-^.^'--"awai" r --- -- - — - ^5 



ADVER TISEMEN TS 



15 



THE GREAT PRODUCTIVE ACHIEVEMENT 
OF THIS CENTURY 



• WHATtSW 

IH THE TWIGS. 




In 1900 the rubber planta- 
tions of the East covered 
1,750 acres and produced 
8,233 pounds of rubber. Now 
they cover 2,000,000 acres, 
producing in 1917, 204,251 
ions of rubber, practically 
80 per cent, of the world's 
annual supply. 

This is the most marvelous 
productive _ development of 
the present century, 

What I Saw in 
The Tropics 

By HENRY C. PEARSON, F.R.G.S. 

Editor of The India Rubber World 



tells accurately, entertainingly and with lavish illustration the story 
of this great plantation achievement. 

The author has been a recognized authority on rubber for 25 
years. ~ He traveled leisurely through the rubber belt around the 
world, carefully investigating wild rubber gathering and rubber 
cultivation everywhere, and describes what he saw in this book, 
naturally, giving most attention to the colossal plantation industry 
in the East. 

This book covers Ceylon, Federated Malay States, Mexico, 
Nicaragua, Costa Rica, Republic of Panama, Colombia, Jamaica 
and Hawaii." "" 

In connection with the text of three hundred pages there are 
over two hundred fine illustrations that serve to enliven the pages 
of the book, as well as to- enhance its value. Sent, postpaid, for 
$3.00. 

' . O - ' 

The India Rubber Publishing Co. 

25 West 45tfe Street* New York 



16 



ADVERTISEMENTS 



Unique Colors Especially Made 

for 

Rubber Makers Use 



USED IN 

Rubber 
Blacks Compounds 

Pneumatic and 
Solid Tires 





Inner Tubes 

Reds Rubber 

Compositions 




Soles 

Yellows and 
Heels 




Leather 
Browns Substitutes 
etc. 



The principal rubber manufacturers in the 
United States, Europe and Japan use these colors. 
Send for samples, prices and particulars. 

Binney & Smith Co. 

SOLE MAKERS 

New York City 



ADVERTISEMENTS 



17 




REG. U. S. PAT. OFF. REG. UNITED KINGDOM 

Published on the 1st of each month by 

THE INDIA RUBBER WORLD 
NEW YORK 

Edited by 
HENRY C. PEARSON, F.R.G.S. 

T7STABLISHED in 1889, to represent the interests of the 
•*— ' manufacturers and distributors of india rubber and allied 
goods in the United States, this journal has broadened its scope 
until it now commands a position of importance as a record of 
the rubber trade and industry in all other countries as well. At 
the same time it has taken a leading position as an exponent of 
the rubber-planting interests and the intelligent exploitation of 
forest rubber, while its statistical department is more fully relied 
upon than any other source of information of this class. 

The publishers believe that today no other special journal 
published covers its field so fully, or commands a circulation so 
widespread or of such a high character. The contents of The 
India Rubber World are, for the most part, expert informa- 
tion, covering whatever is new in factory processes, in rubber 
machinery, in applications of rubber, in company development 
or changes, market conditions, and whatever else may concern 
the entire field of rubber interests. 

As an advertising proposition, it is acknowledged that the 
paper occupies an exceptionally high position as a medium for 
bringing manufacturers and consumers of rubber goods into con- 
tact, and for attracting the attention of manufacturers to new 
appliances and materials. 



YEARLY SUBSCRIPTION: 
UNITED STATES AND MEXICO, - 
ALJ OTHER COUNTRIES, .... 



$3.00 
3.50 



18 ADVERTISEMENTS 



Standards of Excellence and Efficiency 

PICHER 

Sublimed White Lead 
Sublimed Blue Lead 

(Basic Sulphate — Non-Poisonous) 

Rubber Makers' Litharge 

and 



Red Lead 



We shall be pleased to quote 
delivered prices anywhere in the 
United States and for export. 

Warehouses maintained in all 
principal cities, insuring prompt 
service. 



GENERAL OFFICES: 

208 S. LaSalle Street - - - CHICAGO 

EXPORT DEPARTMENT: 

101 Park Avenue - - - NEW YORK 

PLANTS: 

JOPLIN, MO. CINCINNATI, O. NEWARK, N. J. 



ADVERTISEMENTS 19 



A REFINED ELATERITE 

and 

The Highest Grade Hydro-Carbon Compound 



This is a natural product extensively 
used in rubber compounding for the 
past twenty years. 

Made in different consistencies to 
meet your special requirements. 

Adapted to all classes of compounds 
for which formulae will be supplied 
to users of Kapak. 



PUT UP ONLY BY 



Raven Mining Company of Utah 

Marquette Building, Chicago, 111. 

Miners and Refiners of 

ELATERITE and GILSONITE 



20 ADVERTISEMENTS 



SEAVER & CO. 



Established 1882 



3 Tremont Row pympia Bidg.) Boston, Mass. 



Carbon Black 



An inert pigment which 
smoothes and toughens 
tire compounds and mate- 
rially lessens claims for 
adjustments 

Equally adapted to other 
compounds where dura- 
bility and resiliency are 
required 



ADVERTISEMENTS 



21 



<$? of yv 

HIGHEST QUALITY 



THESTAMFORUFACTIGE 



•^ STAMFORD > 
^ CONN v o<^ 



^%RUB^' 



22 



ADVERTISEMENTS 



STRESEN-REUTER & HANCOCK, Inc 

COLORS MINERALS CHEMICALS 



We are in a position to supply promptly, at 
attractive prices, the following materials, both 
in carloads from mill or less carloads from 
either Chicago or Cleveland stocks: 



LITHOPONE 
ZINC OXIDE 
WHITING 
MAGNESIUM 

CARBONATE 
OXIDE 

HYPO 

BLACK 
WHITE 

LITHARGE 



IRON OXIDES 

ALL GRADES 

SULPHUR 

REFINED 
COMMERCIAL 

ANTIMONY SULPHURET 

GOLDEN 
CRIMSON 

CARBON BLACK 
LAMP BLACK 



TALC 
BARYTES 
BLANC FIXE 
GILSONITE 
ANILINE OIL 
COLORS 

CHEMICAL 
MINERAL 

BENZOLE 



We Assure Prompt and Efficient Attention to 
All Inquiries, Large or Small 



Main Office: 



CHICAGO 



CLEVELAND 



Branches: 

NEW YORK 



DETROIT 



TORONTO 



PHILADELPHIA 



ADVERTISEMENTS 26 



The Largest Manufacturers of All 

Grades of Rubber Substitutes 

and Vulcanizing Solutions 




Compounds Made up to Your Specifications 

Our Capacity Sufficient to Meet 
Largest Requirements 

Tyson Brothers, Inc. 

J. A. KENDALL, Western Representative, Akron, Ohio Main Office and Factory: 

Stock Carried in Akron, Ohio WOODBRIDGE, N. J. 



24 



ADVERTISEMENTS 



H. T. WEST CO.,/ivc 

148 STATE ST. BOSTON, MASS. Cable Address: Westant 



Manufacturers and Dealers 



Pine 

Rosin 

Petroleum 



Products 



Distillates, Compounds 
Residuums, Pitches 
Oils and Waxes 



Pine Tars 



Refined, standardized, selected for 
individual requirements 



Carbon Black 
Rosin Oils 



Pure natural gas product, of high- 
est strength and "uniformity; free 
from oils 



Direct distillates and compounds 
to meet any specifications as to 
viscosity, color and rosin acidity 



ROSIN 
PINE OIL 
TAR OIL 
GUMjTHUS 
PINE PITCH 



GUM TURPENTINE 
WOOD TURPENTINE 
CRUDE TURPENTINE 
VENICE TURPENTINE 
BURGUNDY PITCH 



CANDLE TAR 
PARAFFINE WAXES 
PETROLEUM OILS 
COTTONSEED OILS 
VARNISHES 



Shipments in any quantity direct from points of production or 

from local stocks 



ADVERTISEMENTS 



25 



ELATERON MINERAL RUBBER 



I 



UNIFORM 



CLEAN 



A Natural Affinity of Rubber. Used and Endorsed 
by the Majority of Rubber Goods Manufacturers. 
Its use Insures a Homogeneous Compound with a 
Minimum of Labor. ...... 



Granulated 



ELATERON 



Solid 



The Canfield Oil Company 

CLEVELAND ----- OHIO 



The Carter Bell Mfg Co. 



*>Y*'' : &?MZ&¥^&>&< 









t mi 



est 



m 



RUBBER 






ii te, Brown &BIac& 



l^WftSSVAf 



sS&sss 



150 Nassau Street New York 



26 ADVERTISEMENTS 



THE WESTMORELAND CHEMICAL AND COLOR 

COMPANY 

PHILADELPHIA NEW YORK 

S. E. Cor. 22nd and Westmoreland Sis. 150 Nassau Street 

Original Manufacturers in the United States of 



RED OXIDES Ml* OF IRON 




TRADE MARK 



The best compounding;, coloring and coveting values (or the money 
STRICTLY PURE AND IMPALPABLY FINE 



We Manufacture a Variety oi Shades of 

RED OXIDE OF IRON 

Particularly Adapted for 
Rubber Manufacturers ' Use 

Extremely strong in coloring power and 
ground impalpably fine. Also various 
grades of Talc, Soapstone and Asbes- 
tine. Write us for samples and prices. 

C. K. WILLIAMS & CO. 

EASTON, PA. 




Aldehyde Ammonia (Crystals). 

Formaldehyde U. S. P. 40 Per Cent. Volume. 

Formanilid. 

Hexamethylene Tetramine (Powdered). 

Sulphuret of Antimony — Golden, Crimson, Vermilion. 

THE ROESSLER & HASSLACHER CHEMICAL CO. 
100 William Street New York 



ADVERTISEMENTS 27 



TYPKE & KING, Ltd. 

Head Offices and Works: 

CROWN CHEMICAL WORKS 

MITCHAM COMMON, SURREY, ENGLAND 

ANTIMONY SULPHIDES, Golden and Crimson in Many 

Shades with Any Percentage of Free Sulphur. 
LEAD SULPHIDE, in Different Qualities. 
INDIA RUBBER SUBSTITUTES, WHITE and DARK 
SULPHUR PRECIPITATED and SULPHUR LAC 
ARSENIC SULPHIDE - CADMIUM SULPHIDE 

We have manufactured our well known brands of 
the above for upwards of thirty-five years and the 
increasing demand is significant of their quality. 
Samples and quotations willingly given. 

AGENTS' 

Mr. JOSEPH CANTOR, 54 Stone Street, New York 

Messrs. STANLEY DOGGETT, Inc., 11 Cliff Street, New York 



ANTIMONY SULPHURET 

GOLDEN AND CRIMSON 



Mepbisto Crimson An- 
timony has 25% greater 
coloring strength than 
any other crimson An- 
timony on the market. 




Get acquainted with 
this product. We invite 
comparative tests with 
any standard brand of 
European or American 
manufacture. 



RARE METAL PRODUCTS CO. 

BELLEVILLE NEW JERSEY 



28 ADVERTISEMENTS 



Aluminum Flake 

The Colloidal Pigment which Vitalizes the Compound 



Pronounced by experts to be 



The Ideal Rubber Compounding Ingredient 

Lowest in Specific Gravity Highest in Quality 

14 years' persistent use in rubber mills all over the world its best endorsement 

The Aluminum Flake Co., - Akron, Ohio 



. . . ARIAL BRANDS. . . 

RUBBER SUBSTITUTE AND 

CHLORIDE OF SULPHUR 

Superior Qualities, made from best materials and by up-to-date methods. 

White Substitute. Black Substitute. Mono-Chloride Sulphur, for making 

White Rubber Substitute. Proto-Chloride Sulphur, for curing purposes. 

Bi-Chloride Sulphur, for making Brown Rubber Substitute. 

Also Waxes and Earths. Trial orders solicited. 

WILLIAM H. SCHEEL 

159 Maiden Lane and 37 Fletcher Street, - - New York, N. Y. 



THE INDIA RUBBER WORLD 
NEW YORK 

Edited by 
HENRY C. PEARSON, F. R. G. S. 

YEARLY SUBSCRIPTION 

UNITED STATES AND MEXICO, $3.00 

ALL OTHER COUNTRIES, 3.50 



ADVERTISEMENTS 29 



Boston Yarn Company 

BOSTON, MASS. 



Sole Selling Agents for 



BAY STATE COTTON CORPORATION 



Manufacturers of 



AUTOMOBILE TIRE FABRICS 

Sea Islands, Egyptians and Peelers 



Mills at 



LOWELL, MASS. LEROY, N. Y. NEWBURYPORT, MASS. 



30 



ADVERTISEMENTS 








CONNECTICUT MILLS AND OPERATIVES' HOMES 



Connecticut mills Company 



MANUFACTURERS OF 



Fine Sea Island, Egyptian and 
Peeler Tire Fabrics 



OFFICERS: 
TRACY S. LEWIS, pres. a Treas. R. J. CALDWELL, v.-Pres. 

HARRY L. BURRAGE, Chairman O. BUTLER, Sec.-Mgr. 

R. L. FISHER, Asst. Treas. 



PLANTS: 

Danielson, Connecticut 
Taunton, Massachusetts 



1 5 PARK ROW 



NEW YORK 



ADVERTISEMENTS 31 



TIRE FABRICS 

Of Every Description 

Taylor, Armitage & Co., 



INC. 



Equitable Building 

120 Broadway - - New York 

SEA ISLANDS, EGYPTIANS 
PEELERS 

Fabrics to Specification 
PASSAIC COTTON MILLS AMERICAN TIRE FABRIC CO. 



32 ADVERTISEMENTS 



TIRE FABRICS 




The Fabric for Endurance 



MANHASSET MFG. COMPANY 

Providence - Rhode Island 



•Perfect Vulcanization- 



is the most vital factor in the manufacture of rubber goods, 
because the quality and cost of the finished product depend abso- 
lutely upon the uniformity and duration of the cure. 

"TAG" Automatic Controllers 

are recognized as standard equipment in rubber plants all over the world because 
of their super-human accuracy in automatically maintaining proper temperature 
and time in vulcanizing. 

Our dominating position in the rubber field admirably qualifies us to 
economically and efficiently solve your temperature problems. 

Catalogs and expert advice gladly offered to those interested. 



C.xT.TAGLIABUE mfg.co. 



Largest Independent ^HCanufacturers of Automatic Con- 
trollers, Thermometers, etc., for the Rubber Industry 

BROOKLYN, N. Y. CHICAGO BOSTON NEW ORLEANS SAN FRANCISCO 



ADVERTISEMENTS 



33 



"BUFLOVAK" 

VACUUM DRYERS 

Absolutely Dries Without Injury All Kinds of 

Rubber and Compounds 




SHELF DRYER WITH VACUUM PUMP AND CONDENSER 



"Buflovak" Dryers represent "The Highest Attainment in 
Vacuum Dryer Construction." In our Shelf Dryers', the body 
of the Dryer, even on the largest sizes, is made in one piece of our 
special "GUN IRON" metal, thus eliminating the numerous joints 
found in other types and insuring the maintenance of a high vacuum. 

The "Buflovak" Rotary Dryer used for drying reclaimed 
rubber, compounds, and other materials, is noted for its rigid 
construction, high efficiency, and low operating cost. Our catalog 
showing these and other Vacuum Apparatus will be sent on request. 

Buffalo Foundry & Machine Co. 

46 Winchester Ave. BUFFALO, N. Y. 



34 



ADVERTISEMENTS 



RUBBER MACHINERY 



CALENDERS, MILLS, REFINERS, SHEET ERS, 
CRACKERS, WASHERS, PRESSES, HOSE MACHIN- 
ERY, HARD RUBBER MACHINERY, DRIVES, 
SHAFTING, FRICTION CLUTCHES, ETC. 




Engineers and Manufacturers 



A 



FARREL FOUNDRY & MACHINE CO. 

ANSONIA, CONN., U. S. A. 

Cable Address: "FARRELMACH— ANSONIA" * 

Branch Office: 910 UNION NATIONAL BANK BLDG., CLEVELAND, O. 



ADVER TISEMEN TS 



35 




I 



RUBBER WORKERS' TOOLS 




STOCK GAUGES 
HAND ROLLERS and STITCHERS 



=<iuwnuauaittimwim 
CALENDER ROLL ENGRAVING 




STEEL STAMPS 




MOLDS— ALL KINDS 



LATHE CHUCKS 




SPECIAL TOOLS 
ENGRAVING, Etc. 

» THE HOGGSON & 
PETTIS MFG. CO. 

NEW HAVEN, CONN. 

U. S A. 




36 



ADVERTISEMENTS 



Established 1836 Incorporated 1850 

WASHERS, MILLS, REFINERS, CALENDERS 

HYDRAULIC AND SCREW PRESSES 

ACCUMULATORS 

CHILLED AND SAND CAST ROLLS, GEARING, ETC. 



Sole Builders of 



SCHOFIELD PATENT BIAS SHEARS 

BANBURY AUTOMATIC RUBBER MIXERS 

"BIRMINGHAM" TREAD MAKING MACHINES 



Special Machinery Built to Order 



BIRMINGHAM IRON FOUNDRY 

Derby, Conn., U. S. A. 



RUBBER MIXING MACHINERY 





We manufacture Rubber Churns for all classes of 
work, and in all sizes, Heavy Mixers especially adapted 
to Tire manufacturing, mixing machines for dry material, 
Screens, Bolting Reels and Racks of all kinds. 

Write for our catalogs. 

The J. H. Day Company 

CINCINNATI, OHIO 

NEW YORK PHILADELPHIA BOSTON KANSAS CITY CHICAGO BUFFALO 



ADVER T IS EM EN TS 



RUBBER MACHINERY 



An Encyclopedia of Machines Used in Crude Rubber 
Washing, Drying, Preparing of Ingredients, Mixing, 
Preparing of Fabrics, Calendering; Typical Vul- 
canizers, Presses and Molds, Spreaders, Tubing 
Machines; Cements; Reclaimed Rubber; Ex- 
tracting Machines for Wild Rubber; Labo- 
ratory Equipment; Deresination, etc., etc. 

By HENRY C. PEARSON, F. R. G. S. 

Editor of The India Rubber World 



This is the first authoritative book containing com- 
prehensive descriptions of the machinery used in prepa- 
ration of crude, compounded and reclaimed rubber. It 
will be found an extremely valuable reference work for 
rubber factory superintendents, master-mechanics, en- 
gineers, etc. 

The book is substantially bound in cloth, contains 
419 pages, 428 illustrations, and is conveniently in- 
dexed. 

Price $6.00, Postpaid. 

Descriptive circular and table of contents sent on 
application. 

PUBLISHED BY 

THE INDIA RUBBER PUBLISHING COMPANY 

25 West 45th Street, New York 



38 ADVERTISEMENTS 



DAVID A. CUTLER 

17 COVINGTON STREET 

SOUTH BOSTON, MASS. 

EXPERT 

CRUDE RUBBER COMPOUNDING 
FACTORY ORGANIZATION 

OTHER PROBLEMS ALLIED TO 

RUBBER MANUFACTURE 



ADVERTISEMENTS 39 



Dr. Lothar E. Weber 

CONSULTING 

RUBBER 

CHEMIST 

729 Boylston St., Boston, Mass. 



40 ADVERTISEMENTS 



RUBBER CHEMIST 

FREDERICK J. MAYWALD, F. C. S. 

86 PARK PLACE, NEWARK N. \ 

Expert Assistance for the Rubber Manufacturer. I have had 
many years' experience in overcoming factory troubles, and 
have helped many rubber manufacturers to correct errors 
in their methods and formulas, and put their manufactur- 
ing on an efficient and economical basis. I can do the same 
for you.. 

Tested Formulas for Rubber Compounds. 

Experimental Work in a fully equipped laboratory — the only 
independent laboratory of its kind. 

Analyses and Physical Tests. Factory Shrinkage Tests. 

Vacuum Drying (experimental). 



THE CONSULTING COMPANY 

For Rubber Manufacturers 

RECIPES — Formulas, Compounds and Compounding Ingredients. 
ANALYSES — and Physical Tests, on Crude Rubber, Raw Stock, 

Finished Goods. 
FACTORY EFFICIENCY, Equipment Lay-out for New Plants; 

Equipment Adjustment for Existing Plants; Proper 

Equipment and Its Output; Future Enlargement. 
BUILDINGS, Designed for Present Needs, Future Growth, and 

Economical Operation. 
POWER PLANTS— For Rubber Manufacturing. 

Specialists in charge of each department, co-ordinated by 
Practical and Actual Rubber Manufacturing Experience. 
We are at your service. 

THE CONSULTING COMPANY 

Union Central Tower, - - CINCINNATI, OHIO 



ADVERTISEMENTS 



41 



RUBBER MAKERS 

CHEMICALS 



ACIDS 


E 


FYPFIIFRFY 


i 


LITHARGE 


ALUMINUM SILICATE 


1 


lALlLLiEiIyEiA 


1 


L1TH0P0NE 


ANILINE OIL 
ANTIMONY 


1 


The Vulcanizing Speeder 


= 


MAGNESIA 
PETROLATUM 


BARYTES 


1 




1 


RED OXIDE 


BENZOL 


S 


zfln^, 


1 


ROSIN 


BLACKS 


| 


a7Y\ 


E 


SILICA 


BLUES 

CARBON BISULPHIDE 


J 


Ito> 


i 


SOAPSTONE 
SODA ASH 


CAUSTIC SODA 


\ 


W 


E 


SULPHUR 


CHINA CLAY 


1 


>*^ 


| 


SULPHUR CHLORIDE 


GLYCERINE 


1 




1 


TURPENTINE 


GREENS 
HYDROCARBON 


| 


PALMOLINE 


I 


VERMILION 
YELLOWS 


LIME FLOUR 


1 


(Palm Oil Substitute) 


E 


ZINC OXIDE 



ZINC OXIDE 



Katzenbach & Bullock Co. 

440 Washington Street NEW YORK, N. Y. 

BRANCHES 

Boston Trenton Philadelphia Montreal Akron Chicago 

San Francisco Seattle Paris Buenos Ayres 



42 



ADVERTISEMENTS 



S chr a d e r 




Fie. 1 
One-half size 



THE name SCHRADER is a guarantee of quality. The 
reputation which the products of A. SCHRADER' S SON, 
INC., have acquired rests upon seventy-four years of 
efficient service to the trade and public. Since its establish- 
ment in 1844 the SCHRADER firm has had PERFECTION as 
its watchword. SCHRADER UNIVERSAL PNEUMATIC 
TIRE VALVES ate the regular equipment of more than ninety 
per cent, of all automobile, motorcycle and bicycle tires made 
in the United States and Canada, being also extensively used 
by Tire Manufacturers in France and Great Britain. 

SCHRADER UNIVERSAL 
TIRE PRESSURE GAUGES 

Also occupy a preferential position in the favor of Motorists. 
Figure 1 shows the GAUGE with the standard base made to 
fit TIRE VALVES of the American type. As this style of 
GAUGE could not be used to measure the inflation of tires 
fitted with the European style Tire Valves, we have designed 
a GAUGE with the combination base (Fig. 2) which ren- 
ders the SCHRADER UNIVERSAL GAUGE applicable to all 
TIRE VALVES. As illustrated in Figure 2, the GAUGE is 
ready for use on European type Valves. For use on 
the SCHRADER UNIVERSAL VALVE, simply unscrew the 
detachable foot or socket. 

To meet the requirements of the U. S. Army we have 
developed, in conjunction with the Signal Corps, the GAUGE 
illustrated (Fig. 3) , with base at an angle of 90°, for measuring 
pressures in pneumatic truck tires. Oftentimes the free space 
on tiuck tires between the hub and felloe of the wheel is 
rather limited, but with this type of GAUGE the pressure 
can be conveniently ascertained. 

The indicating sleeve of the GAUGE is marked for 
measuring air pressures up to 170 lbs. and can be used in 
connection with tires as large as 8j4 in. in diameter. 



For use abroad, we are prepared 
to furnish an angle base gauge of this 
type fitted with combination base and 
indicating sleeve calibrated in pounds 
and kilograms, similar to illustration 
(Fig. 2). 




Fig. 3 
. One-half size 



ADVER TI SEMEN TS 



43 



Un iversal 



SCHRADER UNIVERSAL VS. EUROPEAN VALVE EQUIPMENT 
Motor Tire Valves 

To meet the demand for a MOTOR TIRE VALVE for 
use abroad, fitted with a SCHRADER UNIVERSAL VALVE 
INSIDE, we are furnishing the No. 2198 VALVE illustrated. 
All the outside fittings on this VALVE, as well as the hous- 
ing part, R, are interchangeable with similar parts used on 
European MOTOR TIRE VALVES. This VALVE is ren- 
dered truly UNIVERSAL, because it is so arranged that the 
ordinary European Valve Check can be used if no SCHRA- 
DER UNIVERSAL VALVE INSIDE is available for replace- 
ment. 





2198 Motor Tire 

Valve 
One-third Size 

prepared to 



Fig. 1 
One-half size 



Bicycle, Motorcycle and Aeroplane Tire Valves 

To permit the use of the air-tight, convenient and effi- 
cient SCHRADER UNIVERSAL VALVE INSIDE in connec- 
tion with Bicycle, Motorcycle and Aeroplane Tires abroad, 

now fitted with Wood's type Valves, we are 

furnish VALVE PLUGS as illustrated. 

The straight VALVE PLUG (Fig. 1) is intended for use 
with Wood's Valves on Bicycles and Motorcycles, and the bent 
VALVE PLUG (Fig. 2) for Wood's Valves on Aeroplane Tires. 
To attach, remove all of the upper parts of the Wood's Valve, 
except those as shown in Fig. 3» Replace with the SCHRADER 
UNIVERSAL VALVE PLUG selected, screwing it into the 
Wood's Valve Stem in just exactly the same way as the upper 
part of the Wood's Valve is attached, being careful to tighten 
the Nut sufficiently so that the Washer of the PLUG will make 
an air-tight joint in the Stem of the Wood's Valve. This arrange- 
ment not only obviates the necessity of constant repairing and 
the annoyance of Valve leakage due to the use of the ordinary 
Wood's Valve, but enables the user to employ a TIRE PRES- 
SURE GAUGE for ascertaining the pressure in his Tires, which 
is impossible when the Wood's Valve is 
used. The No. 2414 COMBINATION* 
VALVE CAP AND FOREIGN CYCLE 
PUMP CONNECTION furnished with 
these VALVE PLUGS possesses two 
functions: First, that of a VALVE CAP 
as shown above; second, as a PUMP 
CONNECTION when the small threaded 
end B is screwed tightly into the VALVE so that an 
ordinary European Cycle Pump may be attached to the end A. 

WE INVITE A TEST BY TIRE MANUFACTURERS IN FOREIGN 
COUNTRIES WHO ARE NOT FAMILIAR WITH OUR PRODUCTS 

A. SCHRADER'S SON, Inc. 
TS3-803 Atlantic Ave., Brooklyn, N. Y. 

LONDON CHICAGO TORONTO 

6 & 8 Earl St., S.W. 1516 S. Wabash Ave. 334 King St., East 




Fig. 3 
One-half size 




Fig. 2 
One-half size 



44 ADVERTISEMENTS 



"SPECIALISTS" 

IN ALL 

COLORS FILLERS 

AND 

CHEMICALS 

FOR 

RUBBER WORKERS 




HEADQUARTERS 

For 

RECOGNIZED STANDARDS 

and always alert to new 

QUALITIES of PROVEN MERIT 

Also 

LARGEST AMERICAN PRODUCERS 

of 

MAGNESIA-MAGNESITE 



L. H. BUTCHER COMPANY, Inc. 

Established 1890 

NEW YORK LOS ANGELES SAN FRANCISCO 



CHEMICALS 

for the 

RUBBER TRADE 



STATES 
BRAND 

Red and 
Golden 
Sulphuret of 
Antimony 




FREE 



Produces 
Tubes with 
Utmost Heat 
Resisting 
Qualities 
^ Long Life 
and 

Numerous 
Selling Points 



Use States Brand Sulphuret of Antimony and Thistle 
Brand Heavy Calcined Magnesia to produce the best 
rubber products. The excellent results obtained 
from these materials encourage their use in every 
branch of the rubber manufacture. 



THISTLE 
BRAND 
Heavy Calcined 
Magnesia 




TRADE MARK. 



MANHATTAN 
BRAND 

Light Calcined 
Magnesia 



Co-operation and service have placed Frazer & Com- 
pany in the enviable position of being always a step 
in advance. 

We have an intimate knowledge of our products and 
their functions. 

Our laboratory is conducted solely for the service of 
the rubber trade at large. 

We are interested in your problems and desire to 
co-operate. 



Frazar & Co. 

New York 



Established 1856 

30 Church Street 



SCOTT TESTERS 



FOR STRENGTH AND ELASTICITY OF 



Yarn 


Cordage 


Chain 


Webbing 


Thread 


Rope 


Cloth 


Leather 


Twine 


Wire 


Fabric 


Rubber 



RECOGNIZED AS THE 

STANDARD 



Scott Testers Used By 

U. S. Bureau of Standards 

U. S. Navy Department 

U. S. Customs Service 

U. S. Bureau of Engraving and Printing 

U. S. Department of Interior 

U. S. Department of Agriculture 

U. S. Army Quartermaster Corp 

U. S. Army Signal Corp 

U. S. Army Chemical Service 

■U. S. Army Gas Defense Service 

U. S. Army Ordnance Department 

Massachusetts Institute of Technology 

Philadelphia Textile School 

Rhode Island School of Design 

Iowa State College 

Bradford Durfee Textile School 

Lowell Textile School 

New Bedford Textile School 

N. C. College of Agriculture and 

Mechanic Arts 
And manufacturers all over the world 




Adaptable to any standard 



HENRY L. SCOTT & CO. 



Established 1899 

PROVIDENCE, R. I. 



U. S. A. 



